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EDDY CURRENTS

Total questions: 15

Worksheet time: 8mins

Name
Class
Date
1.

EDDY CURRENTS ARE PRODUCED IN A MATERIAL WHEN IT IS

a)

HEATED

b)

PLACED IN ELECTRIC FIELD

c)

PLACED IN UNIFORM CONSTANT MAGNETIC FIELD

d)

PLACED IN TIME VARYING MAGNETIC FIELD

2.

EDDY CURRENTS ARE USED IN

a)

INDUCTION FURNACE

b)

ELECTROMAGNETIC BRAKES

c)

SPEEDOMETERS

d)

ALL OF THESE

3.

ASSERTION : IRON LOSS IS MINIMIZED USING LAMINATED CORE

REASON: LAMINATION OF CORE REDUCES EDDY CURRENTS

a)

BOTH ASSERTION AND REASON ARE TRUE AND REASON IS THE CORRECT EXPLANATION OF THE ASSERTION

b)

BOTH ASSERTION AND REASON ARE TRUE AND REASON IS NOT THE CORRECT EXPLANATION OF THE ASSERTION

c)

ASSERTION IS TRUE BUT REASON IS FALSE

d)

ASSERTION AND REASON IS FALSE

4.

CURRENT IN A CIRCUIT FALLS FROM 5A TO 0A IN 0.1S. IF AN AVERAGE EMF 200V IS INDUCED,SELF INDUCTANCE OF THE CIRCUIT IS

a)

1H

b)

2H

c)

3H

d)

4H

5.

SLOTTING PROCESS IN THE METALLIC SHEET CAUSES

a)

INCREASE IN RESISTANCE OF THE PATH FOR CIRCULATION OF CURRENT

b)

DECREASE IN STRENGTH OF EDDY CURRENT

c)

FEEBLE THE ELECTROMAGNETIC DAMPING

d)

ALL OF THESE

6.

IF N IS THE TOTAL NUMBER OF TURNS IN A COIL,THEN THE VALUE OF SELF INDUCTANCE VARIES AS

a)

N^0

b)

N

c)

N^2

d)

N^1/2

7.

WORK DONE IN INCREASING THE CURRENT THROUGH A SOLENOID FROM 0 TO 2A IS 20J .WORK DONE IN INCREASING CURRENT FROM 4 TO 6A IS

a)

60J

b)

100J

c)

80J

d)

120J

8.

WHICH OF THE FOLLOWING IS NOT BASED ON THE APPLICATION OF EDDY CURRENTS

a)

TANGENT GALVANOMETER

b)

SPEEDOMETER

c)

DEAD BEAT GALVANOMETER

d)

ENERGY METER

9.

INDUCTION FURNACE CAN BE USED TO

a)

MIX DIFFERENT METALS

b)

UTILISED TO PREPARE ALLOYS

c)

TO COOK FOOD

10.

Inductance depends only on

a)

the geometry of the coil

b)

intrinsic material properties

c)

current flowing through the inductor

d)

both a and b

11.

Inductance is a

a)

vector quantity

b)

scalar quantity

12.

SI unit of inductance is

a)

ohm

b)

farad

c)

henry

13.

The mutual inductance of a pair of

coils, solenoids, etc., depends on

a)

their separation

b)

relative

orientation

c)

their separation as well as relative

orientation

14.

If we fill the inside of the solenoid with a material of relative permeability

μr (for example soft iron, which has a high value of relative permiability),

then,

a)

L=μ0μrN2Al

b)

L=μ0n2Al/μr

c)

L=μ0μrn2Al

d)

L=μ0μrAl/n2

15.

Consider the case of currents flowing simultaneously in two nearby coils.the emf induced in coil 1 is given by

a)
b)
c)
d)

both a and b

e)

all the above