Question 1.
The average value of a cover a complete cycle is:
(a) l₀
(b) \(\frac{l_0}{2}\)
(c) \(\frac{l_0}{√2}\)
(d) zero

Answer

Answer: (d) zero

---

Question 2.
Power factor of an ac circuit is a measure of:
(a) virtual power
(b) power lost in the circuit
(c) mean power
(d) all the above

Answer

Answer: (b) power lost in the circuit

---

Question 3.
The dimensional formula of L/R is similar to that of:
(a) frequency
(b) time
(c) length
(d) none of these

Answer

Answer: (b) time

---

Question 4.
Which of the following has dimensions different from the rest?
(a) L/R
(b) \(\frac{1}{RC}\)
(c) \(\sqrt{LC}\)
(d) RC

Answer

Answer: (b) \(\frac{1}{RC}\)

---

Question 5.
The dimensional formula of impedance is;
(a) [ML²T^-2A^-2]
(b) [ML²T^-3A^-2]
(c) [ML²T^-2A^-1]
(d) [ML²T^-2A^-3]

Answer

Answer: (b) [ML²T^-3A^-2]

---

Question 6.
Energy dissipates in LCR circuit in :
(a) L only
(b) C only
(c) R only
(d) All of the above

Answer

Answer: (c) R only

---

Question 7.
An iron core transformer with a turns ratio of 8 : 1 has 120 V applied across the primary. The voltage across the
(a) 15 V
(b) 120 V
(c) 180 V
(d) 960 V

Answer

Answer: (a) 15 V

---

Question 8.
What is the ratio of inductive and capacitance reactances in an ac circuit?
(a) 1
(b) ω²L
(c) ω²LC
(d) l

Answer

Answer: (c) ω²LC

---

Question 9.
An acceptor circuit is :
(a) series resonant circuit
(b) parallel resonant circuit
(c) LCR circuit
(d) None of these

Answer

Answer: (a) series resonant circuit

---

Question 10.
A broadcast circute broadcasts at 300 m band. A condenser of capacitance 2.4 lµF is available. The value of the inductance required for resonant circuit is:
(a) 10^-4 H
(b) 10^-8 H
(c) 10^-6 H
(d) 10^-2 H

Answer

Answer: (b) 10^-8 H

---

Question 11.
In series resonant circuit:
(a) reactance is zero
(b) current is zero
(c) voltage is zero
(d) None of these

Answer

Answer: (d) None of these

---

Question 12.
In parallel resonant circuit:
(a) impedance is very high
(b) current is very high
(c) voltage is very high
(d) None of these

Answer

Answer: (a) impedance is very high

---

Question 13.
The no. of turns in the primary coil of a transformer is 200 and the no. of turns in the secondary is 10. If 240 V a.c. is applied to primary, the output from the secondary
(a) 6 V
(b) 12 V
(c) 24 V
(d) 48 V

Answer

Answer: (b) 12 V

---

Question 14.
Transformer works on the principle of:
(a) convertor
(b) invertor
(c) mutual induction
(d) self-induction

Answer

Answer: (c) mutual induction

---

Question 15.
Which of the following effects is not shown in alternating current ?
(a) Chemical effect
(b) Magnetic effect
(c) Heating current
(d) All of these

Answer

Answer: (a) Chemical effect

---

Question 16.
An ac ammeter connected in series in an ac circuit reads 5A. The peak value of current:
(a) 5 A
(b) 5√2A
(c) \(\frac{5}{√5}\) A
(d) zero

Answer

Answer: (b) 5√2A

---

Question 17.
The phase difference b/w the A.C. and e.m.f. \(\frac{π}{2}\) Which of the following can not be the instituent of the circuit?
(a) LC
(b) L alone
(c) C alone
(d) RL

Answer

Answer: (d) RL

---

Question 18.
The Q factor of an LCR circuit at resonance is :
(a) \(\sqrt{R^2+ω^2L^2}\)
(b) \(\sqrt{R^2+(\frac{1}{cω}})^2\)
(c) \(\frac{ω_rL}{R}\)
(d) \(\sqrt{R^2+\frac{1}{c^2ω^2}}\)

Answer

Answer: (c) \(\frac{ω_rL}{R}\)

---

Question 19.
Faraday constant:
(a) depends on the amount of the electrolyte
(b) depends on the current in the electrolyte
(c) is a universal constant
(d) depends on the amount of charge passed through the electrolyte

Answer

Answer: (c) is a universal constant

---

Question 20.
The natural frequency of an L -C-Circuit is equal to :
(a) \(\frac{\sqrt{LC}}{2π}\)
(b) \(\frac{1}{3π\sqrt{LC}}\)
(c) \(\frac{1}{2π}\sqrt{\frac{L}{C}}\)
(d) \(\frac{1}{2π}\sqrt{\frac{C}{L}}\)

Answer

Answer: (b) \(\frac{1}{3π\sqrt{LC}}\)

---

Question 21.
In the series L-C-R circuit, the voltmeter and ammeter readings are:

(a) V = 100 Volts, I = 2A
(b) V = 100 Volts, I = 5A
(c) V = 1000 Volts, I = 2A
(d) V = 300 Volts, I = 1A

Answer

Answer: (a) V = 100 Volts, I = 2A

---

Question 22.
The band width of a series resonant circuit is :
(a) f₀/Q₀
(b) \(\frac{R}{2πL}\)
(c) \(\frac{R}{4πL}\)
(d) 4R

Answer

Answer: (a) f₀/Q₀

---

Question 23.
A rejector circuit is:
(a) series resonant circuit
(b) parallel resonant circuit
(c) LCR circuit
(d) None of these

Answer

Answer: (b) parallel resonant circuit

---

Question 24.
The inductive reactance of an inductor coil of \(\frac{1}{π}\) H at 50 Hz is:
(a) \(\frac{50}{π}\) Ω
(b) \(\frac{π}{50}\) Ω
(c) 100 Ω
(d) 50 Ω

Answer

Answer: (c) 100 Ω

---

Question 25.
In pure inductive circuit current
(a) lags behind emf by π/2
(b) leads the emf by π/2
(c) lags behind emf by π
(d) leads the emf by π

Answer

Answer: (a) lags behind emf by π/2

---

Question 26.
The current through an inductor of 1H is given by I = 3t sin t. The voltage across the inductor of 1 H is:
(a) 3 sin t + 3 cos t
(b) 3 sin t + 3t cos t
(c) 3 cos t + t sin t
(d) 3t cos t + sin t

Answer

Answer: (b) 3 sin t + 3t cos t

---

Question 27.
Two coils X and Y are connected in series across a 240 V, 50 Hz supply. The resistance of X is 5Ω and inductance of Y is 0.02 H. The power consumed is 3 kW and the power factor is 0.75. The impedance of the circuit is:
(a) 0.144 Ω
(b) 1.44 Ω
(c) 14.4 Ω
(d) 144 Ω

Answer

Answer: (c) 14.4 Ω

---

Question 28.
In the above problem, the value of the resistance of the coil Y is:
(a) 0.58 Ω
(b) 5.8 Ω
(c) 1.16 Ω
(d) 11.6 Ω

Answer

Answer: (b) 5.8 Ω

---

Question 29.
An electric circuit containing capacitor only suffers:
(a) equal resistance for A.C. and D.C.
(b) Resistance of A.C. > Resistance of D.C.
(c) Resistance for A.C. < Resistance of D.C.
(d) offers infinite resistance for D.C.

Answer

Answer: (d) offers infinite resistance for D.C.

---

Question 30.
The average power dissipation in pure inductance or capacitance is:
(a) \(\frac{1}{2}\) LI²
(b) \(\frac{3}{2}\) CV²
(c) either (a) or (b)
(d) zero

Answer

Answer: (d) zero

---