Acc to Ohms law V=IR but it is only applicable when our resistance R is constant, as in case of transformer we take impedence which is equivalent to resistance is not constant it varies with system parameters that why Ohms law not applicable in case of transformer

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Dec 6, 2017
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Electrical kida

**Description :** Which of the following theorems enables a number of voltage (or current) source to be combined directly into a single voltage (or current) source. (1) compensation theorem (2) reciprocity theorem (3) superposition theorem (4) Millman's theorem

**Last Answer :** Which of the following theorems enables a number of voltage (or current) source to be combined directly into a single voltage (or current) source. (1) compensation theorem (2) reciprocity theorem (3) superposition theorem (4) Millman's theorem

**Description :** Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

**Last Answer :** 1) Voltage ratio: The voltages in primary and secondary winding is proportional to number of turns in primary and secondary respectively. So, the voltage ratio is same as transformation ratio. V2/V1 = N2 ... as transformation ratio of transformer. It is denoted by K. K = N2/N1

**Description :** Step-down transformer converts high voltage and low current into: (A) How voltage and high current (B) High voltage and low current (C) Low voltage and high current (D) None of the above

**Last Answer :** Step-down transformer converts high voltage and low current into: Low voltage and high current

**Description :** Analyze the effect of supply voltage on performance of LED as regards current, Lumen output, efficacy and life.

**Last Answer :** 1) Effect on Current:- In LED current depends upon supply voltage, if voltage get changes then current also change but this change in current will be control by resistors which are connected in series. 2) ... 4) Effect on Life:- If supply voltage is not stable then life of LED get reduced.

**Description :** With the help of N-channel JFET describe the effect of input voltage VGS on output current ID.

**Last Answer :** Working of N channel FET: * When a voltage is applied between the drain and source with a DC supply (VDD), the electrons flows from source to drain through narrow channel ... where the channel gets completely blocked and the drain current becomes zero is called pinch- off voltage.

**Description :** Define: i) Input Offset Voltage ii) Input offset Current iii) Input Bias Current iv) Output offset voltage

**Last Answer :** Definition of parameters of OPAMP is follows: i) Input Offset Voltage: Input offset voltage is defined as the voltage that must be applied between the two input terminals of an OPAMP to null or ... to ground) and output voltage is obtained non zero such voltage is output offset voltage of opamp.

**Description :** A linear network has a current input 4cos(ω t + 20º)A and a voltage output 10 cos(ωt +110º) V. Determine the associated impedance.

**Last Answer :** Solution

**Description :** What kills, current or voltage?

**Last Answer :** Current would kill. You can actually have thousands of bolts going through you and not even know it. Yes you probably know already voltage is current times resistance. Since your body is a resistor it would take just a small amount of current to create a very high voltage

**Description :** Why inductor current lags inductor voltage ?

**Last Answer :** Inductor is a wire wounding structure having a core material it induces emf which is opposite to the voltage supply and proportional to rate of change of current so current lags the voltage in inductor

**Description :** Explain lagging quantity and leading quantity, explain this concept with voltage and current waveform

**Last Answer :** When two alternating quantities attain their respective zero or peak values simultaneously, the quantities are said to be in-phase quantities. When the quantities do not attain their respective zero or ... current is leading the voltage or the voltage is said to be lagging behind the current.

**Description :** Write the relation between phase and line current, phase and line voltage for Star connection.

**Last Answer :** Line voltage is equal to root three times of phase voltage and line and phase currents are equal in star connection

**Description :** A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of series resistance with source? A) 5.45 Ω B) 6 Ω C) 7.2 Ω D) 6.38 Ω

**Last Answer :** A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of series resistance with source? A) 5.45 Ω B) 6 Ω C) 7.2 Ω D) 6.38 Ω

**Description :** Which of the following is the least expensive protection for over current in low voltage system? (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker

**Last Answer :** Which of the following is the least expensive protection for over current in low voltage system? (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker

**Description :** A current controlled voltage source is equivalent to : (A) series voltage feed -back amplifier (B) shunt current feed -back amplifier (C) shunt voltage feed -back amplifier (D) series current feed -back amplifier

**Last Answer :** A current controlled voltage source is equivalent to : shunt voltage feed -back amplifier

**Description :** A network that consists of at least a voltage source or current source is called A) Active network B) Ideal network C) Sourced network D) Outsourced network

**Last Answer :** A network that consists of at least a voltage source or current source is called Active network

**Description :** The internal resistances of an ideal current source, and an ideal voltage source are, respectively, (A) 0, ∞ (B) ∞, ∞ (C) ∞, 0 (D) 0,0

**Last Answer :** The internal resistances of an ideal current source, and an ideal voltage source are, respectively, ∞, 0

**Description :** A network is said to be under resonance when the voltage and the current at the network input terminals are (A) in phase (B) out of phase (C) in phase quadrature (D) in phase, and have equal magnitudes

**Last Answer :** A network is said to be under resonance when the voltage and the current at the network input terminals are in phase

**Last Answer :** In order that current should flow without causing excessive heating or voltage drop, the relay contacts should have low contact resistance, be clean and smooth, be of sufficient size and proper shape.

**Description :** Why does increase in current mean a decrease in voltage?

**Last Answer :** This is because current flows from high potential to low potential to bring the two diffrent potential to unity , thus a reduced potential (voltage)

**Description :** Electrical shock happens for voltage/current?

**Last Answer :** The severity ofelectric shockdepends on thecurrentflowing through the body, which is a function of the electromotive force (E) involts, and the contact resistance (R) in ohms.

**Description :** A transformer has negative voltage regulation when its load power factor is (1) Zero (2) Unity (3) Leading (4) Lagging

**Last Answer :** 0

**Description :** When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is?

**Last Answer :** If v = 1 volt and i = 1 micro amp, i= 10^(-6) So R = V/I, R= 1/10^(-6) , R= 10^6 And now Conductance G = 1/R So G = 10^(-6) mho..... Answer

**Description :** If resistance is 8 Ohm and current is 16 ampere then what will be the voltage and power?

**Last Answer :** 128 volts ,2048 watts

**Description :** Draw the structural diagram of GTO. Explain briefly the switching behavior of GTO with the help of appropriate voltage and current waveform.

**Last Answer :** Gate Turn Off Thyristor (GTO) Conventional Thyristor can be turned on with gate terminal but can not turn off from gate terminal. But in case of Gate Turn Off Thyristor (GTO), we can turn it on and off ... subdivided as storage period (Ts), fall period (Tp) and tail period (Tt).

**Description :** A 3 -phase, fully controlled, converter is feeding power into a DC load at a constant current of 150 A, the rms value of the current flowing through each thyristor of the converter is

**Last Answer :** Please show the solution for this question

**Description :** When an alternating current passes through an ohmic resistance the electrical power converted into heat is?

**Last Answer :** When an alternating current passes through an ohmic resistance the electrical power converted into heat is true power.

**Last Answer :** In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

**Description :** What is the relationship between power and current?

**Last Answer :** P = I2R Where P = power I = Current R = Resistance This the relationship between current and power.

**Last Answer :** When a conductor carries more current on the surface as compared to core, it is due to skin effect.

**Description :** Find power delivered by voltage source

**Last Answer :** Find power delivered by voltage source

**Description :** Is the power line voltage available in our homes a dc or an ac voltage?

**Last Answer :** The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.

**Description :** An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS

**Last Answer :** An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS

**Description :** An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak Envelope Power? A) 49.98 W B) 79.98 W C) 99.96 W D) 199.93 W

**Last Answer :** An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak Envelope Power? A) 49.98 W B) 79.98 W C) 99.96 W D) 199.93 W

**Description :** In voltage source converter based HVDC transmission system the active power is controlled by changing (A) phase angle of the converter ac input voltage (B) supply frequency of the converter ac input voltage (C) magnitude of the converter ac input voltage (D) DC voltage at the inverter terminals

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**Description :** For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is

**Last Answer :** For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is 25 x 25

**Last Answer :** The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

**Last Answer :** The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to extinguish the arc.

**Description :** Minimum voltage regulation occurs when the power factor of the load is?

**Last Answer :** Minimum voltage regulation occurs when the power factor of the load is leading.

**Description :** In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

**Last Answer :** In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.

**Description :** Why high voltage can reduce power loss?

**Last Answer :** when voltage has increased due to reduced current flow, thus power loss given by ( I^2R) will be low due to reduced current(I^2) provided that resistance (R) is constant.

**Description :** Why high voltage is used in power transmission?

**Last Answer :** The primary reason that power is transmitted at high voltages is to increase efficiency. ... The lower current that accompanies high voltage transmissionreduces resistance in the conductors aselectricity flows ... This means that thin, light-weight wires can beused in long-distance transmission.

**Description :** Justify. Power MOSFET is operated at high enough gate source voltage to minimize the conduction losses.

**Last Answer :** MOSFET is metal oxide field effect transistor. MOSFET is a voltage controlled device. MOSFET is majority carrier device. MOSFET are of two one is n-channel MOSFET and p-channel MOSFET. Gate, ... . Hence, power MOSFET is operated at high enough gate-source voltage to minimize the conduction losses.

**Last Answer :** The voltage regulation in magnetic amplifier type voltage regulator is effected by varying the reactance.

**Description :** The inrush current of a transformer at no load is maximum if the supply voltage is switched on (1) at peak voltage value (2) at zero voltage value (3) at half voltage value (4) at 0.866 time voltage value

**Last Answer :** At 0.866 time voltage value

**Description :** Define: i) Knee voltage ii) Reverse saturation current

**Last Answer :** i) Knee voltage : The applied forward voltage, at which the PN junction starts conducting and current starts increasing exponentially is called knee voltage. It is 0.7V for Si and 0. ... semiconductor diode caused by diffusion of minority carriers from the neutral regions to the depletion region.

**Description :** An A.C. voltage is impressed across a pure resistance of 3.5 ohms in parallel with a pure inductance of impedance of 3.5 ohms?

**Last Answer :** An A.C. voltage is impressed across a pure resistance of 3.5 ohms in parallel with a pure inductance of impedance of 3.5 ohms, both resistance and inductance carry equal currents.

**Description :** The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above

**Last Answer :** The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA

**Last Answer :** The gravity controlled instrument has crowded scale because current is proportional to sine of deflection angle.

**Description :** What is electric power generation transmission and distribution?

**Last Answer :** Generation: it wrong word at here.because it is no generation it is conversion of one form of energy into electrical form.it may by using any type of energy. Transmission is just to ... place to other by providing some modifications And distribution means use of this energy for any purpose.

**Description :** What happens when you reverse the direction of the current in an electromagnet?

**Last Answer :** When you reverse current direction in an electromagnet, the magnetic poles will also change.