# Practice Test: Question Set - 03

**1. The law that the induced e.m.f. and current always oppose the cause producing them is due to**

- (A) Faraday

- (B) Lenz

- (C) Newton

- (D) Coulomb

**2. An open coil has**

- (A) Zero resistance and inductance

- (B) Infinite resistance and zero inductance

- (C) Infinite resistance and normal inductance

- (D) Zero resistance and high inductance

**3. Find the force acting on a conductor 3m long carrying a current of 50 amperes at right angles to a magnetic field having a flux density of 0.67 tesla**

- (A) 100 N

- (B) 400 N

- (C) 600 N

- (D) 1000 N

**4. If current in a conductor increases then according to Lenz's law self-induced voltage will**

- (A) Aid the increasing current

- (B) Tend to decrease the amount of current

- (C) Produce current opposite to the increasing current

- (D) Aid the applied voltage

**5. As per Faraday's laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it**

- (A) Lies perpendicular to the magnetic flux

- (B) Lies in a magnetic field

- (C) Cuts magnetic flux

- (D) Moves parallel to the direction of the
magnetic field

**6. An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be**

- (A) 64 A/s

- (B) 32 A/s

- (C) 16 A/s

- (D) 4 A/s

**7. A 500 turns solenoid develops an average induced voltage of 60 V. Over what time interval must a flux change of 0.06 Wb occur to produce such a voltage?**

- (A) 0.01 s

- (B) 0.1 s

- (C) 0.5 s

- (D) 5 s

**8. The self-inductance of the coil may be defined as equal to the e.m.f. induced in volts when the current in the circuit changes at the rate of unit Weber turns.**

- (A) Yes

- (B) No

**9. A coil induces 350 mV when the current changes at the rate of 1 A/s. The value of inductance is**

- (A) 3500 mH

- (B) 350 mH

- (C) 250 mH

- (D) 150 mH

**10. A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is**

- (A) 50 ohms

- (B) 500 ohms

- (C) 1000 ohms

- (D) 5000 ohms

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