This set of Basic Electrical Engineering Multiple Choice Questions & Answers focuses on “Inductance in Terms of Flux Linkages Per Ampere”.
1. Among the following, which is the right formula for inductance?
a) L=emf*t/I
b) L=emf/t*I
c) L=emf*I/t
d) L=emf*t*I
View Answer
Explanation: The average emf induced is proportional to the current per unit time, the constant of proportionality being L. Hence emf=LI/t. Making L the subject of the formula, we get L=emf*t/I.
2. Among the following, which is the right formula for inductance of N turns?
a) L=et/Ni
b) L=N*i *e*t
c) L=Ni/et
d) L=N/iet
View Answer
Explanation: We know that:
emf=NLi/t
Inductance = L = et/N.
3. For a coil having a magnetic circuit of constant reluctance, the flux is ___________ to the current.
a) Directly proportional
b) Inversely proportional
c) Not related
d) Very large compared to
View Answer
Explanation: For a coil having a magnetic circuit of constant reluctance, the flux is directly proportional to the current.
4. For a coil having a magnetic circuit of constant reluctance, if the flux increases, what happens to the current?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
View Answer
Explanation: For a coil having a magnetic circuit of constant reluctance, the flux is directly proportional to the current. Hence as the flux increases, the current also increases.
5. The unit for inductance is ___________
a) Ohm
b) Henry
c) A/m
d) A/s
View Answer
Explanation: The unit of induction is named after a famous scientist Joseph Henry who independently discovered electromagnetic induction.
6. If either the inductance or the rate of change of current is doubled, the induced e.m.f?
a) Remains constant
b) Becomes zero
c) Doubles
d) Becomes half
View Answer
Explanation: If either the inductance or the rate of change of current is doubled, the induced e.m.f. becomes double because of emf=LI/t.
7. If the current changes from 5A to 3A in 2 seconds and the inductance is 10H, calculate the emf.
a) 5V
b) 10V
c) 15V
d) 20V
View Answer
Explanation: We know that:
emf=L(i2-i1)/t
Substituting the values from the question, we get emf=10V.
8. If the current changes from 5A to 3A in x sec and inductance is 10H. The emf is 10V, calculate the value of x.
a) 2s
b) 3s
c) 4s
d) 5s
View Answer
Explanation: We know that:
emf=L(i2-i1)/t
Substituting the values from the question, we get x=2s.
9. If the current changes from 3A to 5A in 2s and the emf is 10V. Calculate the inductance.
a) 10H
b) 20H
c) 30H
d) 40H
View Answer
Explanation: If the current changes from 5A to 3A in 2s and the emf is 10V. Calculate the inductance.
Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.
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