Test A - Electromagnetic Induction (EMI), Class 12 Physics Class 12 Notes | EduRev

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1. Write the dimensional formula for magnetic flux. [1]
2. Why the coil of a dead beat galvanometer is wound on a metal frame ? [1]
3. A lamp connected in parallel with a large inductor glows brilliantly before going off, when the
switch is put off. Why ? [1]
4. How can the effect of eddy current be minimized. [1]
5. A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along
the axis of the ring. Will the acceleration of the falling magnet be equal to, greater than or less than
to gravity ? Why ? [2]
S
N
6. A copper loop and an aluminium loop are removed from a magnetic field in the same time interval.
In which loop will the induced emf and induced current be greater ? Why ? [2]
7. A coil of area 0.04 m
2
 having 1000 turns is suspended perpendicular to a magnetic field
of 5.0 × 10
–5
 wb/m
2
. It is rotated through 90° in 0.02 sec. calculate the average emf induced
in it ? [2]
8. A conducting rod of 1 m length moves with a frequency of 50 rev/sec, with one end at the centre and
the other end at the circumference of a circular metallic ring of radius 1m, about an axis passing
through the centre of the coil and perpendicular to the plane of coil. A constant magnetic field
parallel to the axis is present everywhere. What is the emf developed between the centre and the
metallic ring. [B = 1 Wb/m
2
]. [2]
9. How are eddy currents produced ? Give two applications of eddy currents. [2]
10. Define coefficient of self induction. Write its dimensional formula. [2]
11. Define the terms mutual inductance. Write  its SI unit. Give three factors on which the coefficient of
mutual inductance between a pair of coil depends. [3]
12. A circular loop of radius 0.3 cm lies parallel to a much bigger loop of radius 20 cm. The centre of the
small loop is on the axis of bigger loop. The distance between their centres is 15 cm.
(i) What is the flux linking in the bigger loop if a current of 2 A flows through smaller loop ?
(ii) What is the mutual inductance of two loops ? [3]
13. A small flat search coil of area 2 cm
2
 with 25 close turns placed between the poles of a strong
magnet normally to the magnetic field. The field is suddenly switched off. The total charge flown in
the coil is 7.5 mC. The resistance of the coil is 0.50 ?. Find the magnitude of the field of the
magnet ? [3]
ELECTROMAGNETIC INDUCTIONS T E S T - A
X I I
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