Electromagnetic Induction - Electrical engineering multiple choice questions and answers for competitive exams

1. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as
(a)     self-inductance
(b)     mutual inductance
(c)     series aiding inductance
(d)     capacitance

Ans: a

2. 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
(e) cuts magnetic flux
(d) moves parallel to the direction of the magnetic field

Ans: c

3. Which of the following circuit element stores energy in the electromagnetic field ?
(a) Inductance      
(b) Condenser
(c) Variable resistor
(d) Resistance

Ans: a

4. The inductance of a coil will increase under all the following conditions except
(a) when more length for the same number of turns is provided
(6) when the number of turns of the coil increase
(c) when more area for each turn is provided
(d) when permeability of the core increases

Ans: a

5. Higher the self-inductance of a coil,
(a) lesser its weber-turns
(b) lower the e.m.f. induced
(c) greater the flux produced by it
(d) longer the delay in establishing steady current through it
Ans: d

6. In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
(a) increase
(b) decrease
(c) remain the same
(d) initially increase and then decrease
Ans: b

7. 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
Ans: b

8. Both the number of turns and the core length of an inductive coil are doubled.
Its self-inductance will be
(a) unaffected
(b) doubled
(c) halved
(d) quadrupled
Ans: b

9. 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 cur-rent
(c) produce current opposite to the in-creasing current
(d) aid the applied voltage
Ans: c

10. The direction of incViced e.m.f. can be found by
(a) Laplace's law  
(b) Lenz's law
(c) Fleming's right hand rule
(d) Kirchhoff s voltage law
Ans: b

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