Questions
22
If current in a conductor increases then according to Lenz’s law self-induced voltage will
Answer: produce current opposite to the in-creasing current
23
Both the number of turns and the core length of an inductive coil are doubled.
Its self-inductance will be
Answer: doubled
25
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
Answer: decrease
26
Higher the self-inductance of a coil,
Answer: longer the delay in establishing steady current through it
27
The inductance of a coil will increase under all the following conditions except
Answer: when more length for the same number of turns is provided
28
Which of the following circuit element stores energy in the electromagnetic field ?
Answer: Inductance
29
As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it
Answer: cuts magnetic flux
30
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
Answer: self-inductance
31
The four factors determining inductance are the number of turns, coil length, coil area, and:
Answer: permeability
32
What is the number of turns required in the secondary winding for a transformer when 120 volts is applied to a 2400-turn primary to produce 7.5 Vac at the secondary?
Answer: 150 turns
33
Which two values are plotted on a B-H curve graph?
Answer: flux density and magnetizing force
35
Electromagnetism is the:
Answer: magnetic field action with a current-carrying wire
37
The polarity of induced voltage while a field is collapsing is:
Answer: opposite to the force creating it
38
What does Faraday's law concern?
Answer: a magnetic field cutting a conductor
39
A henry value divided by a circuit resistive value provides the:
Answer: induced voltage amplitude
40
Faraday's law states that the:
Answer: emf depends on the rate of cutting flux
