This sets of mcqs contains questions on Electromagnetism for preparing your objectives exams..
SET 1 of Electromagnetism MCQs with answers
1. The lines of force produced by coil completing their path through air, instead of intended path is called
a. useful flux
b. saturated flux
c. air flux
d. leakage flux
ans: d
2. The bulging of lines of force in air gap in a magnetic circuit is called
a. leaking flux
b. merging
c. fringing
d. scattering
ans: c
3. Relative permeability of vacuum is
a. 4π × 10-7 H/m
b. 1 H/m
c. 1
d. ¼ H/m
ans: c
4.MMF in magnetic circuit is analogous to
a. electric current in electric circuit
b. current density in conductor
c. electromotive force
d. resistance in electric circuit
ans:c
5. Reluctance is analogous to
a. emf in electric circuit
b. resistivity
c. conductivity
d. resistance in electric circuit
ans: d
6. The magnetic reluctance of a material
a. increases with increasing cross sectional area of material
b. does not vary with increasing the cross sectional area
c. decreases with increasing cross sectional area of material
d. decreases with increasing the length of material
ans: c
7. The correct relation stated as following is
a. ф = 𝑁 𝑙/𝑎µ0µ𝑟
b. NI = B× l/a µ0µr
c. N=H×l
d. NI = ф × l/µ0µr a
ans: d
8. The permeance in a magnetic circuit corresponds to
a. resistance in an electric circuit
b. emf in an electric circuit
c. conductivity in electric circuit
d. conductance in an electric circuit
ans: d
9. The ampere turns are
a. the product of the number of turns and current of the coil
b. the number of turns of a coil through which current is flowing
c. the currents of all turns of the coil
d. the turns of transformer winding
ans:a
10. What will be the current flowing through the ring shaped air core when number of turns is 800 and ampere turns are 3200
a. 0.25
b. 2.5
c. 4.0
d. 0.4
ans:c
SET 2 of Electromagnetism MCQs with answers
11. Leakage factor is defined as the ratio of
a. flux in air gap by total flux
b. Total flux by useful flux
c. airgp flux by useful flux
d. total flux by flux produced by solenoid
ans: b
12. Effect of fringing in magnetic circuit is
a. it increases flux density
b. its effective area of air gap decreases
c. it decreases flux density
d. none of above
ans:c
13.The force experienced by unit north pole when placed at point in a magnetic field is called
a. magnetic field strength at that point
b. exerted force at that point
c.flux
d. magnetic field
ans:a
14. The mechanical force acting on current carrying on conductor when placed in magnetic field is given by relation
a. F= N dф/dt
b. F= Blv sinӨ
c. F= BIL sinӨ
d. F=L di/dt
ans: c
15. Which of the following has the highest magnetic permeability?
a. paramagnetic substances
b. diamagnetic substances
c. ferromagnetic substances
d. vacuum
ans: c
16. The perfect insulator for magnetic lines of force is
a. copper
b. rubber
c. glass
d. none of these
ans: d
17. The force between two parallel current carrying conductors is given by relation
a. I1I2 ×2× 10-7× l/d
b. I1dl /I2 ×4π× 10-7
c. I1I2 /2π× 10-7
d. I12×4× 10-7 ld
ans: a
18. The magnitude of force experienced by current carrying conductor placed in magnetic field depends on
a. value of flux
b. magnitude of current flowing through conductor
c. direction of current
d. all of above
ans: d
19.Two current carrying conductor lying parallel and close to each other. They are carrying current in the opposite direction. The force between them is
a. repulsive
b. Attractive
c. Zero
d. none of these
ans: a
20. The emf induced in a conductor of length 1 meter moving at a right angles to a uniform magnetic field of flux density 1.5 wb/m2 with velocity of 50 m/s is.
a. 0
b.1.5 v
c. 75 v
d. 100 v
ans:c
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