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Posted on Sep 17, 2010

2. When a inductive coil connected to a 200 V, 50Hz ac supply with 10A current flowing through it dissipates 1000 watts then which of the following will have least value in ohms a.) Resistanceb.) Reactance c.) Impedance d.) None 3. Oscillator crystal are made of ? a.) Silicon b.) Germanium c.) Quartz d.) None 4. For small size, high frequency coils, the most common core material is-a. )Airb. )Ferrite c.) Powdered ion d.) Steel 5. If we have a parallel plate capacitor of plate area ?A? and plate separatoin t and having a capacity C and a metallic plate r of area A and of negligible thickness is introduced in the capacitor at a distance from either of the two plates as shown in the given figure then the capacity of the capacitor will become ? a.) b.) C c.) 2C d.) 4C 6. A superconductor is a ? a.) A material showing perfect conductivity and Meissner effect below a critical temperature b.) A conductor having zero resistance c.) A perfect conductor with highest di-magnetic susceptibility d.) A perfect conductor which becomes resistance when the current density through it exceeds a critical value 7. When an inductor tunes at 200 KHz with 624 pF capacitor and at 600 KHz with 60.4 pF capacitor then the self capacitance of the inductor would be ? a) 8.05 pF b) 10.05pF c.) 16.01pF d.) 20.01pF 8. Sparking occur when a load is switched off because the circuit has high ? a.) Inductance b.) Capacitance c.) Resistance d.) None 9. Sparking between contacts can be reduced by inserting a ? a.) Resistance in the line b.) Capacitor in series with contacts c.) Capacitor in parallel with contacts d.) None 10. RF amplifier of an A.M. receiver is normally biased in ? a.) Class ?A? b.) Class ?b? c.) Class ?C? d.) None 11. The value of gate voltage for the operation of enhancement of only N channel MOSFET has to be ? a.) High positive b.) High negative c.) Low positive d.) Zero 12. The input gate current of a FET is ? a.) a few microamperes b.) negligibly small c.) a few milliamperes d.) a few amperes 13. In the following fig. with R = 30k, the value of current through 2 K resistor is ? a.) 25 mA b.) 40 mA c.) 25/16 mA d.) 10 mA 14. A step recovery diode ? a.) has on extremely short recovery time b.) conducts equally well in both directions c.) is mainly used as a harmonic generator d.) is an ideal rectifiers of high frequency signals 15. In order to get maximum undistorted output signal from CE amplifier with VCC 10V, the value of VCE (Q) should be approximatelya.) 0.1V b.) 5V c.) 10V d) V 16. In a FET the electrode, which corresponds to collector in bipolar transistor, is ? a.) source b.) drain c.) gate d.) none 17. The device which acts like an NPN and a PNP transistor connected base to base and emitter to collector is ?a.) Triacb.) UJT c.) Diac d.) SCR 18. A typical optical fibre has ? a.) High refractive index core and low refractive index cladding b.) Low refractive index core and high refractive index cladding c.) Both a and b d.) None 19. In the following figure circuit diagram of an op-amp based is shown. The ratio is equal to ? a.) 9 b.) 11 c.) 10 d.) 21 20. When a loud speaker is connected across the terminals A and B of the network shown in the fig. then its impedance to obtain maximum power dissipation in it will be ? a.) 3 ? j1 b.) 3 + j9 c.) 7.5 + j 2.5 d.) 7.5 ? j 2.5 21. In the lattice network, the value of R for the maximum power transfer to the load ? a.) 5 b.) 6.5 c.) 8 d.) 9 22. For a lossy transmission line short circuited at the receiving end, the input impedance is given by (Z0 is the characteristic impedance, √ is the propagation constant and l is the length of the line-a.) Z0 cot h √lb.) Z0 cot √l c.) Z0 tan h.√ l d.) Z0 tan √l 23. The approximate thickness of the radome wall should be ?a.) λb.) λ/4 c.) λ/2 d.) λ/8 24. A relatively permanent information is stored in a. ) ROM b.) RAM c.) PROM d.) Volatile memory 25. The rise time of the RC network shown in the given figure is approximately equal to ? b.) RC c.) 2RC d.) 4RC 26. If in the network shown in the fig. initially a steady state is attained by closing the switch ?s? and then if the switch is opened at t = 0, then the current i(t) through the inductor will be ? a.) cos50tA b.) 2A c.) 2cos100tA d.) 2sin50tA 27. When the π network of figure ? I and T-network of figure ? II are equivalent then the values of R1, R2 and R3 will be respectively ? a) 9 , 6 and 6 b.) 6 , 6 and 9 c.) 9 , 6 and 9 d.) 6 , 9 and 6 28. When the impedance matrices of a two port networks are given by and , then if these two networks are connected in series then the impedance matrix of the resulting two-port network will be ? d.) indeterminate 29. Joule/coulomb is the unit of - a.) Electric field potential b.) Potential c .) Charge d.) None of the above 30. The electric field line and equipotential linesa.) Are parallel to each other b.)Are one and same c.) Cut each other orthogonally d.)Can be inclined to each other at any angle 31. For a lossy transmission line short circuited at the receiving end, the input impedance is given by (When Z0 is the characteristic impendence γ is the propagation constant and L is the length of the line 32. When two equal positive point charges are placed along X- axis at X1 and ?X1 respectively then the electric field vector at a point P on the positive Y-axis will be directeda.) In the +x direction b.) In the ?x direction c. ) In the +y direction d.) In the ?y direction 33. The directions of and in TEM mode transmission line with respect to the direction of propagation area.) Both and are transverse to the direction of propagation b.) is and are transverse and h has a component in the direction of propagation c.) is entirely transverse and has a component in the direction of propagation d. ) is entirely transverse and has a component in the direction of propagation 34. The lowest TM mode in a rectangular waveguide of cross ?section a x b with a>b will bea.) TM01 b.)TE10 c.) TM112 d.)TE11 35. When a transmitter in a free space radiates a mean power of ?p? watts uniformly in all directions then at a distance d sufficiently far from the source in plane the electric field E should be related to p and d as ? 36. . When a dipole antenna was radiating with some excitation in free space radiating a certain amount of the power v if then this antenna is immersed in a lake where water is non-dissipative but has a dielectric constant of 81, then the radiated power with the same excitation will be a.) Decrease to finite non-zero value b.)Remain the same c. )Increase d.)Decrease to zero 37. When a (75 ? j40) load is connected to a coaxial line of Z0 = 75 at 6MHz then the load matching on the line can be accomplished by connectinga.) A short ? circuited stub at the load b.)An inductance at the load c. )A short circuited stub at a specific distance from the load d.)none of the above 38. As compared to analog multimeters, digital multimeters are ?a.) less accurateb.) more accurate c.) equally accurate d.) none. 39. When a signal of 10 mV at 75 MHz is to be measured then which of the following instruments can be used ?a.) VTVMb.) Cathode ray oscilloscope c.) Moving iron voltmeter d.) Digital multimeter 40. Which of the following statement is true about two wattmeter method for power measurement in three phase current ?a.) power can be measured using two wattmeter method only for star connected three phase circuits.b.) when two meter show indentical readings, in the power factor is 0.5. c.) when power factor is unit, one of the wattmeter reads zero d.) when the reading of the two wattmeters are equal but of opposite sign, then the power factor is zero ? 41. When a capacitance transducer has two plates of area 5cm2 each, separated by an air gap of 2mm than the displacement sensitivity in pf/cm due to gap change would be ?a.) 11.1b.) 44.2 c.) 52.3 d.) 66.3 42. The Q of a radio coil ?a.) is independent of frequencyb.) increases monotonically as frequency increases c.) decreases monotonically as frequency increases d.) increases upto a certain frequency and then decreases beyond that frequency 43. When a generator of internal impedance and operating at 1GHz feeds a load via a coaxial line of characteristic impedance 50 ohm then the voltage wave ratio on the feed line is ?a.) 0.5b.) 1.5 c.) 2.5 d.) 1.75 44. The coding system typically used in digital telemetry is ?a.) PPM (pulse position modulation)b.) PAM (pulse amplitude modulation) c.) PCM (pulse code modulation) d.) PDM (pulse duration modulation) 45. Radiation pyrometers are used for the measurement of temperature in the range of ? a.) -2000C to 5000C b.) 00C to 5000C c.) 5000C to 12000C d.) 12000C to 25000C 46. In the given figure band structure is shown. It is of ? a.) Gallium Avesenide (GaAs) b.) Silicon (Si) c.) Copper (Cu) d.) Germanium (Ge) 47. When anode is positive with respect to cathode in an SCR, the numbers of blocked p-n junction is ? a.) 1 b.) 2 c.) 3 d.) 4 48. The circuit symbol for a GTO is a. b. c. d. 49. In the given fig. mark out the type of Cyclo converters a.) 1 phase to 1 phase with continuous conduction b.) 1 phase to 1 phase with discontinuous conduction c.) step up device d.) 3 phase to 1 phase device In the given fig. A-1, C=5, m H and C=20 m F, C is initially charged to 200 V. After the switch. S is closed at t = 0 the maximum value of current and the time at which it reaches this value are respectively. a.) 400 A, 15.707 mS 50. b.) 50 A, 30 mSc.) 100 A, 62.828 mSd.) 400 A, 31.414 mS 51. 50. In the given circuit the maximum current in the main SCR M can bea.) 200 A b.) 170.7 A c.) 141.4 A d.) 70.7 A 52. The transfer function of an amplifier is given by The high 3-db frequency of the amplifier will approximately a.) 5850 KHZ b.)585 KHZ c.) 5850 HZ d.)585HZ 53. In comparison to full wave rectifier with two diodes the four divide bridge rectifier has the dominant advantage of - a). Higher current carrying b.)Lower ripple factor c.) Higher efficiency d.)Lower peak increase voltage require 54. Power output increase in a class-c amplifiera.) If the conduction angle decrease b).If the conduction angle increase c.) Are not governed by the conduction angle d.)None of the above 55. A transistor with hie = 1.5 k and hfe = 75 is used in an emitter follower circuit where R1 and R2 are used for normal biasing . Approximate value of it?s current amplification isa.) 75b.)76 c.)75/76 d.)-75 56. Amplifier of class B has high theoretical efficiency of 78.5 percent becausea.) It is biased almost to saturation b.)Its quiescent current is low c.)It?s output is an exact replica of it?s input d.)It is biased well below cut off 57. The coupling that produces minimum interference with frequency response isa.) Direct coupling b.)Impedance coupling c.) R C coupling d.)Transformer coupling 58. In the circuit shown in the given figure Rf provides a.) Current series feedback b.)Current shunt feedback c.) Voltage series feedback d.)Voltage shunt feedback 59. Mark the correct relation for the junction transistor 60. Data in the serial form can be converted into parallel form by using ?a.) PISO shift registerb.) SOIP shift register c.) SIPO shift register d.) POIS shift register 61. PROMs are used to store-a.) bulk informationb.) information to be accessed rarely c.) sequence information d.) relatively permanent information 62. The horizontal axis in a 3 bit unipolar D/A converter represents-a.) Output bit combinationb.) analog output voltage c.) input bit combination d.) none of the above 63. ?Not allowed? condition in NAND gate SR flip flop is ?a.) s = 0, R = 0b.) s = 1, R = 1 c.) s = 0, R = 1 d.) s = 1, R = 0 64. Name the fastest logic family-a) TTLb.) RTL c.) DCTL d.) ECL 65. Equation corresponding to De Morgan?s theorem in Boolean Algebra is ? a.) (A+B) (A+B) = AA + AB + BA + BB c.) A + AB = A d.) None of the above 66. In the given fig find radix of the system ? a.) 2 b.) 4 c.) 6 d.) 8 67. Modems are used for data transmission telephone lines to ?a.) increase the transmission capacityb) improve noice performance c.) incorporate error control coding d.) eliminate dc component in the transmitted signal 68. The figure of a control system is shown. The maximum value of gain K for which the system is stable is- a.) b.) 3 c.) 4 d.) 5 69. Identify the example of open-loop system-a.) A windscreen wiperb.) Aqualung c.) Respiratory system of an animal d.) A system for controlling Anti-rocket missiles. 70. Consider the following expressions indicating the step or impulse response of an initially relaxed control system-1. (5 ? 4e-2+) u(t)2. (e-2t +5) (u(t)) 3 .ς(t) + 8e-2t u(t) 4 . ς(t) + 4e-2t 4(t) Those which correspond to the step and impulse response of the same system includea.) 1&3 b.) 1&4 c.) 2&4 d.) 1&4 71. A system is described by To test its stability by Lyapunov?s method the following V functions are considered. Mark the most suitable V-function in this casea.) Only V1 b.) Only V2 c.) Both V1 and V2 d.) Neither V1 nor v2 72. Identity the polar plot of a typical type zero system with open loop transfer function 73. The scattering matrix of a magic ?tee shown in the given figure is- 74. Which is the following relate to rational transfer function of a system-1. Ratio of Fourier transform of output to input with zero initial conditions.2. Ratio of Laplace transform of output to input with zero initial conditions. 3. Laplace transform of system impulse response. 4. Laplace transform of system unit step response select the correct answer using the codes given below. Codes a.) 1 and 4 b.) 2 and 3 c.) 1 and 3 d.) 2 and 4 75. For the signal g (t) ? 10 cos (50 pt) cos2 (150at)The Nyquist sampling state in t seconds isa.) 150 samples per second b.) 200 samples per second c.) 300 samples per second d.) 350 samples per second 76. In the case of a 70 MHz 1F carries for a transponder band width of 36 MHz; energy must lie between ? MHz.a.) 34 and 106b.) 52. And 88 c.) 106 and 142 d.) 34 and 142 77. Radar used to eliminate clutter in navigational application is ?a.) Pulse radarb.) Tracking radar c.) MTI radar d.) Mono pulse radar 78. The 1.55 mm windows is not yet in use with fiber optic systems because ?a.) The attenuation is higher than at 0.85 mm b) The attenuation is higher than at 1.3mm c.) Suitable laser devices have not yet been developed d.) It does not lend itself to wavelength multiplexing 79. Pre-emphasis in FM systems involves-a.) Compression of the modulating signalb.) Expansion of the modulating signal c.) Amplification of lower frequency components of the modulating signal. d.) Amplification of higher frequency components of the modulating signal. 80. In a terrestrial microwave system transmission of signals is achieved through-a.) reflection from the ionosphereb.) line of sight mode c) reflection from the ground d.) diffraction from the stratosphere. 81. Casse grain feed is used with a parabolic reflector toa.) increase the gain of the systemb). increase the bandwidth of the system c.) reduce the size of the main reflector d.) allow the feed to be placed at a convenient point. 82. In most microwave communication link rain drop attenuation is caused due to-a.) scattering of microwaves by water drops of specific size.b) scattering of microwaves by a collection of droplets acing as a single body. c.) absorption of microwaves by water and consequent heating of the liquid d.) absorption of the microwaves by water vapor in the atmosphere. 83. Circuit in the given figure represents. ? a.) an astable multivibrator b.) A monostable multivibrator c.) Voltage controlled oscillator d.) Ramp generator 84. . . D = r is-a.) Maxwell?s 1st equationb.) Maxwell?s II equation c.) Maxwell?s III equation d.) Maxwell?s IV equation 85. In a rectangular wave-guide which TM mode exists-a.) TM00b.) TM01 c.) Tm10 d.) TM11 86. In directional coupler a portion of power two velliry fram port 1) to port 2) is coupled to.a). port 4b). port 3 c.) port 2. d.) port 3 & 4. 87. For high power i.e. 10 w to 50 kw measurement ? a.) Barometer are used b.) Thermisters are used c.) Calorimetric technique d.) Calorimetric watt meter technique used 88. The difference between TWT & klystron is ? a.) In TWT electrons are in contact with RF field for long time & in klystron for short time b.) In klystron electrons are in contact with RF field for long time & in TWT for short time c.) In klystron there is no contact in RF field & electrons while in TWT there is contact d.) In TWT phase is no contact is RF field & electrons while in klystron there is contact 89. Which one is most suitable for transmission through wave guidea.) Hown antennas b.) Bioconical antennas c.) helical antenna d. )Discone 90. The skip distance of microwave is given by ? a.) b. ) c.) d.) 91. How many general purpose registers 8085mpa.) 4 b.) 6 c.) 8 c.) 10 92. 8085 mP has no. of addressing modesa.) 2 b.) 3 c.) 4 d.) 5 93. What will be status of z and c y flag after execution of SUB A instruction a.) z = 0, cy = 0 b.) z = 0, cy = 1 c.) z = 1, cy = 0 d.) z = 1, cy = 1 94. Microprocessor accept interrupt only if. a.) interrupt flip flop disabled. b.) when INTA signal is low. c. ) interrupt flip flop enabled. d.) none of above. 95. Microprogramming is a technique a.) for programming the microprocessor b.) for writing small programs efficiently c.) for programming the control steps of computer d.) for programming o/p / i/p 96. High level programs like C are converted into machine language with the help ofa.) interpreterb.) compiler c.) operating d.) system 97. (10110011)2 = (?)8a.) 253b.) 263 c.) 273 d.) 283 98. A Not gate at the output of AND gate converts AND gate into-a.) NANDb.) NOR c.) AND d.) NOPE. 99. The O/P of a logic gate is the gate must be-a.) ANDb.) OR c.) NAND d.) X-OR 100. A symbol of JK flip flop is- 101. A demultiplener-a.) has multiple i/p and single o/pb.) has multiple i/p and multiple o/p c.) has multiple i/p and multiple o/p d.) has single i/p and single o/p 102. . Which of the following best describes the authour`s attitude toward fairy tales ?a.) fascinationb.) open approval. c.) Indulgent tolerance. d.) Scornful. 103. What type of sentence is this ?Hurray! We won the matcha.) Exclamatory b.) assertive c.) Negative d.) Affirmative 104. Before which of the following word will you put ?a?a.) hourb.) M. A. c.) Umbrella d.) Man 105. The noun form of ?fresh? is ?a.) freshlyb.) freshen c.) fresheners d.) fresh itself 106. The word ?clang? is an example of ?a.) Simileb.) inversion c.) onomatopoeia d.) irony 107. The Forbes magazine acclaimed Azim Premji as richest India?s is the chairman of-a.) Pentafour softwareb) Infosys c.) IBM d.) Wipro 108. Bharat Ratna award for the year 2001 goes to-a.) Lata Mangeshkar and Zakeer Hussainb.) Zakeer Hussain and Bismillah Khan c.) Bismillah Khan and Lata Mangeshkar d.) Lata Mangeshkar and Ustad Amzad Ali Khan 109. Mr. George W-Bush takes over as ?? President of the united states of America succeeding Mr. Bill Clinton-a.) 42nd b.) 43rd c.) 40th d.) 45th 110. New Chief Minister of Pondicherry is-a.) T. Venkat Naidub.) K. Hari Harh c.) N. Rengaswany d.) M. Mudliar 111. No court has the jurisdiction to interfere with the election process once set in motion by the Election commission. This is enshrined in Article-a.) 311b.) 329 c.) 356 d.) 365 112. Ostrich is a-a.) Running birdb.) Flying bird c) Swimming bird d.) Migratory bird 113. The main atmospheric gas responsible for green house is-a.) Oxygenb.) Nitrogen c.) Ozone d.) Carbon-dioxide 114. Which of the following is not a Kharif Crop-a.) Riceb.) groundnut c.) Sugarcane d.) gram 115. The function of World Bank is to-a.) Help in reconstruction and development of world economyb.) Facilitate poor countries to trade on concessional rates c.) Promote growth of international trade and equilibrium in balance of payments d.) Ease trade barriers and establish rule of fair trade 116. Speed of sound is maximum in-a. )Waterb.) Air c.) Steel d.) Vacuum 117. ?Long years ago we made a trust with destiny.? Whose words are these-a.) Subhash Chandra Boseb.) Jawaharlal Nehru c.) Lajpat Rai d.) Bhagat Singh 118. Durand cup is associated with-a.) Hockeyb.) Tennis c.) Football d.) Badminton 119. Rabindranath Tagore was awarded the Nobel Prize in literature in the year.a.) 1908b.) 1910 c.) 1913 d.) 1914 120. India successfully conducted its first underground nuclear experiment at Pokhran in Rajas than on-a.) May 18, 1975b.) May 20, 1974 c) May 17, 1974 d.) May 17, 1974 121. An emergency loan of $ 500 million to help reconstruct infrastructure in earth quake devastated Gujarat approved by-a.) Asian development Bankb.) World Bank c.) Swiss Bank d.) Reserve Bank of India

5 Related Answers

otacon

Damen Wong

  • 1950 Answers
  • Posted on Jan 02, 2008

SOURCE: no voice, no map display beyond 30 mile range, slow to compute

Hi,

Did you try updating your unit's firmware?

http://www8.garmin.com/products/webupdater/howtoinstall.jsp

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Anonymous

  • 3 Answers
  • Posted on Sep 07, 2008

SOURCE: 60CSX altimeter problem

I fixed this problem in my 76cs by doing a factory reset.
It kept all my maps, but dumped all waypoints and tracks.
After that, the altimieter problem was fixed.

Your reset will vary, and can easily be found on google. Mine was

http://gpsinformation.us/gps60c/g76Creview.html
Complete Reset:
Press "Enter, Page, and Power on keys" to get to the message that says, "Do you really want to erase all user data". Before you say "YES", I would strongly recommend you download your waypoints, tracks, and routes to a computer, and write down your settings as they will all be erased or reset. Of course your software version will remain the same, and
any downloaded maps will still be there.

And then: From the Trip Computer Page, while there push the scroll key up, right, down, & then left to get to a diagnostic screen used by Garmin Techs. I would not recommend playing with this screen too much, less you want to ship your unit back to Garmin for repair!

Anonymous

  • 240 Answers
  • Posted on Apr 05, 2009

SOURCE: need to pick perfect amp

I suggest to use separate amps to your sub, get a 2 channel amp for your sub and 4 channel amps for your speakers.

Here are my Top 5

  • Lanzar -OPTI4000D
  • MA Audio- HK-4000D
  • JL Audio 1000/1V2
  • OPti 22.2 Power Amp
  • AudioBahn-A5100T

Anonymous

  • 52 Answers
  • Posted on Jun 30, 2009

SOURCE: bridging amp/sub

wire speakers in series google it to find diagrams

Anonymous

  • 655 Answers
  • Posted on Jul 21, 2009

SOURCE: i have 3 hifonics zeus

Hello king3132,

Three 4 ohm subs can be wired parallel for a 1.34 ohm final load or series for a 12 ohm load. If you have the channels of the amp bridged, I hope that the subs are connected in series because the Sony XM-2200GTX is NOT rated for or stable at 1.34 ohms. It's only stable down to 4 ohms.

You definitely will not get the maximum potential of the subs from that amp. They can handle 400 watts RMS each (total 1,200 watts) and the amp is only capable of 500 watts RMS into 4 ohms (less at higher impedance), so each sub could only be getting a maximum of 166.6 watts RMS.

Hope this helps.

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Related Questions:

0helpful
1answer

How does a walk through metal detector work?

Almost all airport metal detectors are based on pulse induction (PI). Typical PI systems use a coil of wire on one side of the arch as the transmitter and receiver. This technology sends powerful, short bursts (pulses) of current through the coil of wire. Each pulse generates a brief magnetic field.
https://detectorly.com/demystifying-metal-detector-revolutionary-technologies-behind
0helpful
1answer

What is the motor hp?

Please see below courtesy of engineeringtoolbox.com

Electrical power is in general rated in watt (W) or horsepower (HP). A horsepower is a unit of power equal to 746 watts or 33000 lb ft per minute (or 550 lb ft per second).
A watt is equal to the power produced by a current of 1 amp across the potential difference of 1 volt. A watt is 1/746 of 1 horsepower.
Even if the watt is the base unit of electrical power, it is common to rate motor power in either horsepower or kilowatts.

Power in Watts

Direct Current Electric power supply to a direct current (DC) motor:
PkW = ?m U I / 1000 (1)
where
PkW = power (kW)
?m = motor efficiency
U = voltage (V)
I = current (A, amps)
Electric power supply to a alternating current (AC) motor:
Single Phase PkW = ?m U I PF / 1000 (1b)
where
PF = Power Factor
Two Phase Four Wire PkW = ?m 2 U I PF / 1000 (1c)
Three Phase PkW = ?m 1.73 U I PF / 1000 (1d)

Power in Horsepower

Horse power can be expressed as:
Php = PkW / 0.746 (2)
or
Php = (?m U I / 1000) / 0.746
= ?m U I / 746 (2b)
where
Php = horsepower (hp)
Feb 03, 2016 • Boating
0helpful
1answer

What is my current rate

Which current are you referring to ??......



If you think of an electrical device as a piece of plumbing, voltage is the amount of water that you send down into the pipe, resistance is the pipe's relative width or narrowness, and current is the speed with which the water flows.
Power measures the water's relative difficulty or ease making its way through the pipe.
You relate all these values to one another using a common set of physics equations known as Ohm's law.
If you need to calculate electricity's current flow, you'll need to have at least two of the three values -- voltage, resistance or power -- listed above.

Calculate current flow using voltage and resistance.
According to Ohm's law, you can express electricity's current in amps as a ratio of its voltage in volts to the resistance of the device it's flowing through in ohms -- I = E/R, respectively.
For example, if you want to know the current flow of 220 V of electricity as it flows through a laptop computer with 80 ohms of resistance, you would simply plug these values into the equation as follows: I = 220/80 = 2.75 amps.
Calculate current flow using power and resistance.
Ohm's law also states that electrical current, "I," is equal to the square root of the power dissipated as it travels through the device divided by that device's resistance.
If a light bulb dissipates 80 watts of power and has a resistance of 55 ohms, you can calculate the electricity's current as follows: I = sqrt(80/55) = sqrt(1.4545) = 1.20 amps.

Calculate current flow using power and voltage.
If you have a space heater which dissipates 420 watts of power when it takes in 120 V of electricity, Ohm's law states you can calculate this electricity's current using the equation "I = P/E." For this example, compute current like so: I =420/120 = 3.5 amps.

http://www.the12volt.com/ohm/ohmslaw.asp
1helpful
1answer

AC surge current?

you are missing the voltage supply here to get an definitive answer
for 240 volts drawing 4.8 amps the required wattage is 1152
for 120 volts the wattage is 576 watts
for 120 volts with a current of 900 watts , it equates to 7.5 amps
with 240 volts with a current of 1150 watts , it equates to 4.79 amps
so you can see the problem by not stating the supply voltage
get access to an cable clamp amp meter / watt meter from an electrician and read the current on starting the ac unit
if it exceeds 900 watts for 120 volts or 1150 for 240 volts , consider a bigger generator
1helpful
1answer

Volfenhag ZX4725 i am buying this subwoofer and

No the LOWER the resistance the MORE Output or Draw, If say it is 100 Watts into 4 Ohms, if you used a 2 ohm speaker it would draw 200 watts.(only if capable of delivering that amount of power) The LOWER the Resistance, the HIGHER the Current Draw. WATTS = AMPS x VOLTS. (This is not strictly true with amplifiers output though, as it is an AC Current, and a "Reactive" load, it has, Inductance, Capacitance and Resistance, all in one.and is worked out via a Formula) see below. http://en.wikipedia.org/wiki/Audio_power

http://www.hometheaterhifi.com/volume_1_1/v1n1spk.html

Now with Dual Voice Coils, Essentially, you can think of these speakers as TWO speakers in ONE enclosure. As such, They are basically TWO Speakers. Please see the website below it explains everything for you. http://www.diyaudioandvideo.com/FAQ/Wiring/
Everything is a function of Resistance and Ohms law.
Current (I) = Voltage (E) divided by Resistance(R).
Voltage = Current Multiplied by Resistance.
Resistance = Voltage divides by Current.
0helpful
1answer

Need to convert 120V AC/DC current to 120V AC 60Hz 15W

there is no such thing as "ac/dc" current-its either one or the other--if its a 120 Volts then chances are it is AC already-at 60hz---the 15 Watts or any Watts is the amount of draw from the unit-not the power supplied to it- Watts= Volts(supplied)/Amps(being used) if you only want to supply 15 watts then reduce the amps (with a fuse) to .125amps
2helpful
2answers

Front speakers stopped working

They are probably blown. Here is instructions for testing a blown speaker.

Get yourself an electric meter, like a multi meter they sell at your local Radio Shack. Set it to read ohms (impedance). Make sure your speaker is off and put one meter lead on each of the two terminals. If your speaker is blown, it will read infinite impedance. If your speaker is good to go, it will read 1.0.
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Need small microwave for inverter on houseboat

Look at the rating sticker on the oven and use the AC power rating as your guide. The cooking power of the oven is not important, but the power it needs from the AC supply is. Voltage times current is the supply power needed (watts), and you want an oven that will draw less than the inverter's continuous rating, less any power being used by other appliances.

For instance, a microwave rated for 120 volts AC at 10 amps needs 1200 watts. Your inverter would be OK with this as long as other devices aren't using more than another 1000 watts. You can't use the inverter's peak rating. That's only for brief bursts, like when the microwave first kicks on and draws some extra current.

Any mid-power (600 watts or so) oven should be OK.
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Conecting to 120 volts AC

If you want to get more precise, figure out everything in terms of power (watts).

Basic electrical rule 1, 2 and 3:

voltage x current = power

or re-arranged:

current = power divided by voltage

or re-arranged:

voltage = power divided by current


For example, 12V X 2 amps = 24 watts.

or another example, 400 watts divided by 120 Volts = 3.33 amps

A 55W headlight that uses 12V would draw 55 /12 = 4.6 amps @ 12V

A 55 watt light bulb in a lamp at home would draw 55 / 120 = 0.46 amps @ 120V


As the previous post mentioned, inverters are not perfect when convertering 12V into 120V. If the converter consumes 1000W from the 12V battery, then a 90% effecient converter would generate 900W of 120V AC power best case. The other 100W is lost primarily as heat.

The other thing that gets tricky is that these ratings and the formula above are used for resistive loads, like light bulbs or hair dryers. Anything with a motor or transformer is considered an inductive load and can get much more tricky to calculate.

Consequently you need to give your self a safety margin when figuring out how big an inverter you need.

How does work in a practical sense?

Lets say you want an inverter for TV, DVD and Sat. Receiver. Look at the back of TV or in the manual. It should say how many watts it consumes. Lets say it is 400W. The DVD might be 100W and the Sat. receiver 50W - just as an example.

400 + 100 + 50 = 550 Watts. (just as an example)

You might think, well no problem, I'll use a 600 Watt inverter and have 50 watts left over. Depending on your inverter, that 600W might really be 600 x 90% effecient = 540 Watts of AC, less a 20% margin of error for the inductive transformers in the electronic of the TV, DVD and Sat. receiver 540 - 20% = 432 Watts.

Now you can see your 600 Watt inverter isn't big enough to do the job.

If we really need 550 watts of AC, add 10% to make up the effiency loss, then add a safety margin for inductive loads.

550 + 10% = 605 + 20% = 726 Watts.

Sounds more like an 800W inverter fits the job.

What does that mean in terms of wiring the 12V batteries to the inverter?

from the formula above:

current = power divided by voltage

In our example, we have an 800W inverter that runs on 12V

The current would thererfore be:

current = power divided by voltage
current = 800 watts divided by 12V
current = 66 amps.

That is important info because you can not use light gauge wire to carry 66 amps worth of 12V to the inverter nor could you use a 20A fuse to protect your inverter.

Now that's a lot of science for a guy who just wants to run a toaster on an inverter right?

800W / 120V = 6.66 amps

Using garryp's ratio 11:1, 6.66 x 11 = 73 amps.

That is a good ratio with a good safety margin.

This is all just MHO and should not taken as solid technical advise. In other words, don't blame me if you blow yourself up.
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