Description : A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current decreases.

**Answer** : The question seems to be wrong. Increase in frequency would actually decrease the current through the Inductor. This happens because inductive reactance Xl is directly proportional to frequency. And if frequency increases the value of Xl would ... vice versa. Xl= 2*pi*f*L I=E/Z Z=sqrt(R^2+Xl^2)

Description : The inductance of a power transmission line increases with (A) decrease in line length. (B) increase in conductor diameter. (C) increase in spacing between phase conductors. (D) increase in load current carried by conductors.

**Answer** : The inductance of a power transmission line increases with increase in spacing between phase conductors.

**Answer** : The size of the induced electromotive force is proportional to the rate of change of theelectric current. ... The self-inductance of a coil, or simply its inductance, may thus be thought of as electromagnetic inertia, a property that opposes changes both in currents and in magnetic fields.

Description : The threshold frequency is the frequency below which : (1) photo current increases with voltage (2) photo current decreases with voltage (3) photo electric emission is not possible (4) photo current is constant

**Answer** : photo electric emission is not possible

Description : The frequency of the Trichel’s pulses increases by: a. Increasing the gas pressure b. Decreasing the gas pressure c. Increasing the temperature d. Unaffected by any one of the above

**Answer** : The frequency of the Trichel’s pulses increases by: a. Increasing the gas pressure b. Decreasing the gas pressure c. Increasing the temperature d. Unaffected by any one of the above

Description : An a.c series circuit has resistance of 10ohm, inductance of 0.1H and capacitance of 10µf, voltage applied to circuit is 200V. find (i) Resonant frequency (ii) Current at resonance (iii) Power at resonance

**Answer** : Solution: For RLC series circuit

Description : As the temperature of the air increases from 0 degrees C to 20 degrees C, the wavelength of a sound made by a tuning fork of fixed frequency does which of the following? Does the wavelength w) increase x) decrease y) remain the same z) increase up to a maximum, then remain constant

**Answer** : ANSWER: W -- INCREASE

Description : When a person sitting on a swing stands up on the swing, the frequency of oscillation (1) decreases (2) increases (3) becomes infinite (4) does not change

**Answer** : increases

Description : Describe with working of LCR meter for measurement of inductance.

**Answer** : working of LCR:- A LCR meter (Inductance (L), Capacitance (C), and Resistance (R) test equipment used to measure the inductance, capacitance and, resistance of a component. It works on the ... in parallel (as would be encountered in measuring a capacitor with a leaky dielectric) [Q setting ]

Description : A coil of 500 turns is linked with a flux of 25 mwb, when carries a current of 12.5A. Calculate the value of self-inductance.

**Answer** : Ans: Self-Inductance: L = NΦ /I = 500 × 25 × 10-3 / 12.5 = 1 H

Description : In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a ……… …………through the switching devices over short interval of time. A) constant current B) constant voltage C) constant power D) none of the (A), (B), (C)

**Answer** : In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a constant current through the switching devices over short interval of time.

Description : A coil of inductance 240 mH and resistance 75 Ohm is connected in parallel with a capacitor across a 30 V, variable frequency supply. The current drawn by the circuit is found to be minimum when the supply frequency is 1 kHz. The ... (A) 40, 400 Hz (B) 10, 100 Hz (C) 20, 50 Hz (D) 50, 20 Hz

**Answer** : A coil of inductance 240 mH and resistance 75 Ohm is connected in parallel with a capacitor across a 30 V, variable frequency supply. The current drawn by the circuit is found to be minimum ... supply frequency is 1 kHz. The approximate values of Q-factor and bandwidth are, respectively 20, 50 Hz

Description : A parallel combination of capacitance C and resistance R is connected in series with inductance L and small resistance r. Under what condition will the circuit be non-reactive? (A) C=LR (B) C=LR2 (C) C=L/R2 (D) C=L/R

Description : The current i(t), through a 10 Ω resistor in series with an inductance, is given by I(t) = 3 + 4sin (100t + 450 ) + 4 sin(300t +600) amperes. The RMS values of the current and power dissipation ... respectively (B) √35 A, 350 W respectively (C) 5 A, 250 W respectively (D) 11 A, 1210 W respectively

Description : Why does bleeding occur through the nose in high mountainous regions ? (1) The pressure of blood in capillaries is greater than the outside pressure (2) The pressure at high altitudes is ... of a person increases at high altitudes (4) The blood pressure fluctuates and finally decreases drastically

**Answer** : The blood pressure of a person increases at high altitudes

Description : Why does the speed of a DC shunt motor decrease as the load increases?

**Answer** : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description : Why is voltage increases before transmission?

Description : Why should local oscillator frequency be greater than signal frequency in AM receiver? Also explain why IF has constant value?

**Answer** : Reason for LO frequency to be greater than signal frequency The local oscillator frequency (f0) is made greater than signal frequency (Fs) in radio receiver: Local oscillator frequency range is 995 ... frequency of desired signal because the IF is constant and same for all the incoming RF signal.

Description : Explain why reception for high frequency band is better during night time.

**Answer** : In sky wave propagation, the transmitted signal travels into the upper atmosphere where it is bent or reflected back to earth. This bending or reflection of signal takes place due to the presence ... reflected signal and hence the reception for high frequency band is better during night time.

**Answer** : Because India uses 220-230volt In USA there they uses 110volt

Description : Why the cutoff frequency is taken for 3db?

**Answer** : MOSFET provides better efficiency at high frequency and its high speed switching losses are less hence MOSFET is used for high frequency.

Description : Which among the given statement is/are CORRECT. (a) Avalanche breakdown voltage increases with temperature (b) Zener breakdown voltage decreases with temperature A) Only (a) B) Only (b) C) Both (a) & (b) D) None of (a) & (b)

**Answer** : Which among the given statement is/are CORRECT. (a) Avalanche breakdown voltage increases with temperature (b) Zener breakdown voltage decreases with temperature A) Only (a) B) Only (b) C) Both (a) & (b) D) None of (a) & (b)

Description : At temperatures above a limiting value, the energy of lattice vibrations, in a conductor, increases linearly with temperature so that resistivity increases linearly with temperature. In this region, this limiting value of temperature is called

**Answer** : At temperatures above a limiting value, the energy of lattice vibrations, in a conductor, increases linearly with temperature so that resistivity increases linearly with temperature. In this region, this limiting value of temperature is called Debye temperature

Description : The electrical conductivity of a semiconductor increases with increase in temperature because (a) the carrier concentration increases (b) the mobility of carrier increases (c) both carrier concentration and mobility increase (d) the band gap decreases

**Answer** : The electrical conductivity of a semiconductor increases with increase in temperature because the carrier concentration increases

Description : The depth of penetration of a wave in a lossy dielectric medium increases with

**Answer** : The depth of penetration of a wave in a lossy dielectric medium increases with Increasing wavelength

Description : 220kV three phase transmission line is 60 km long. The resistance is 15 Ohms per phase and the inductance is j 30 Ohms. 1- Calculate : voltage regulation, TL line power losses and efficiency when ... for 0.85, calculate zise of the required capacitor and the same parameters which were in part 1

Description : The inductance of a long solenoid of length 1000 mm wound uniformly with 3000 turns on a cylindrical paper tube of 60 mm diameter is (A) 3.2 µH (B) 3.2 mH (C) 32.0 mH (D) 3.2 H

**Answer** : The inductance of a long solenoid of length 1000 mm wound uniformly with 3000 turns on a cylindrical paper tube of 60 mm diameter is 32.0 mH

Description : effect of inductance and capacitance on performance of transmission line.

**Answer** : Following are the effect on performance of transmission line: 1. Due to inductance (L) voltage drop in transmission line produces. 2. Capacitor (C) draws charging current ... , transmission line efficiency, voltage regulation & also power factor of transmission line gets affected.

Description : What is inductance?

**Answer** : Inductance is the property of Material by which it opposes the any change of magnitude or direction of electric current passing through the conductor. The inductance is denoted by L. The unit of inductance is Henry (H).

Description : Self inductance formula

**Answer** : Self inductance formula

Description : Self induced voltage across an inductance

**Answer** : Self induced voltage across an inductance

Description : State the effects of errors in dynamometer type wattmeter due to i) pc- inductance ii) pc- capacitance iii) mutual inductance iv) Connection.

**Answer** : Errors in wattmeter: i) pc - inductance: Pressure coil inductance causes wattmeter to read more power than actual . ii) pc-capacitance: The wattmeter reads less power. iii) ... iv) Connection: In uncompensated wattmeter , the reading of wattmeter includes the powerloss in coils.

Description : Define :i) Self inductance ii) Coefficient of self induction

**Answer** : i) Self-inductance: It is the property by virtue of which a coil opposes change in current flowing through it by inducing an emf in it such that its effect is to circulate current (induced current) that produces a magnetic field ... N = di/dt N = Φ/I It is expressed in henry.

Description : An iron cored inductance coil can be modelled, over a normal operating range of networks ,as A) non-Linear bilateral element B) linear bilateral element C) linear time varying element D) non-linear time invariant element

**Answer** : An iron cored inductance coil can be modelled, over a normal operating range of networks ,as linear bilateral element

Description : These self inductance of a circuit is defined as twice the work done against the induced e.m.f. on establishing unit current in the coil. If the current to be established in the coil is doubled, the work done ... induced e.m.f. will be 1. Doubled 2. Halved 3. four times 4. Quarter times

**Answer** : These self inductance of a circuit is defined as twice the work done against the induced e.m.f. on establishing unit current in the coil. If the current to be established in the coil is doubled, the work done against the induced e.m.f. will be four times

Description : lt the length, number of turns and area of a coil are doubled, the inductance of the coil

**Answer** : lt the length, number of turns and area of a coil are doubled, the inductance of the coil is quadrupled

Description : A network consists of several inductances connected in parallel. The equivalent inductance of the network is given by (A) the sum of the individual inductances. (B) the reciprocal of the ... of individual inductances. (D) the reciprocal of the sum of reciprocals of individual inductances.

**Answer** : A network consists of several inductances connected in parallel. The equivalent inductance of the network is given by the reciprocal of the sum of reciprocals of individual inductances.

Description : What is the value of Inductance of a coil that induces 20 V when the current through the coil changes from 12 to 20 A in 2 seconds? A. 2 H B. 3 H C. 4 H D. 5 H

**Answer** : 5 H is the value of Inductance of a coil that induces 20 V when the current through the coil changes from 12 to 20 A in 2 seconds.

Description : A 220 kV, 3 phase transmission line is 60 km long. The resistance is 0.15 ohm / km and the inductance is 1.4 mH / km. Use the short line model to find the power at the sending end when the line is supplying a three ... at 0.8 pf lagging at 220 kV. (A) 5.58MW (B) 80MW (C) 85.58MW (D) 74.42 MW

Description : A three phase 50 Hz, 400 kV transmission line is 300 km long. The line inductance is 0.97 mH/km per phase and capacitance is 0.0115 mF/km per phase. Assume a loss less line. Determine the line wavelength (a line phase constant). (A) 1250 km (B) 6578 km (C) 4990 km (D) 2445 km

Description : A choke coil having resistance RΩ and of inductance L Henry is shunted by a capacitor of C farads. The dynamic impedance of the resonant circuit would be: (A) R/LC (B) C/RL (C) L/RC (D) 1/RLC

Description : The differential coupling of two coils in series connection has self-inductance of 2 mH & 4 mH & a mutual inductance of 0.15 mH. The equivalent inductance of the combination is: (A) 5.7 mH (B) 5.85 mH (C) 6 mH (D) 6.15 mH

**Answer** : An undesirable side effect of motional inductance of large conduction specimens is eddy currents.

Description : A series RLC circuit has a resistance of 50 , inductance of 0.4H and a capacitor of 10µF. The circuit is connected across a 100V supply. The resonance frequency and the current through the resistance are

**Answer** : A series RLC circuit has a resistance of 50 , inductance of 0.4H and a capacitor of 10µF. The circuit is connected across a 100V supply. The resonance frequency and the current through the resistance are 500 rad/s and 2A.

Description : Two similar coils have self inductance of 1 mH each. Coefficient of coupling is 0.5. The mutual inductance M is

**Answer** : Two similar coils have self inductance of 1 mH each. Coefficient of coupling is 0.5. The mutual inductance M is 0.5 mH.

**Answer** : Inductance coils are basically designed for High Q.

Description : The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is_______Vs.

**Answer** : The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is 20 Vs

Description : When both the inductance and resistance of a coil are doubled the value of?

**Answer** : When both the inductance and resistance of a coil are doubled the value of time constant remains unchanged.

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