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Worksheets

Machines

Total questions: 10

Worksheet time: 9mins

Name
Class
Date
1.

Thin laminations are used in a machine in order to reduce

a)

Hysteresis losses

b)

Copper losses

c)

Iron losses

d)

Eddy current losses

2.

The emf induced in the dc generator armature winding is

a)

AC and DC

b)

DC

c)

AC

d)

None of the above

3.

Commutator in DC generator is used for

a)

collecting of current

b)

reduce losses

c)

increase efficiency

d)

convert AC armature current in to DC

4.

In DC machine yoke offers

a)

mechanical protection to the machine

b)

flux path completion

c)

produce working flux

d)

both A and B

5.

In DC generators brushes are used for

a)

collecting of voltage

b)

collecting of current without any sparkings

c)

reduce eddy current loss

d)

convert ac armature current in to dc

6.

In a dc machine 4 pole lap winding is used. The number of parallel paths are?

a)

2

b)

8

c)

1

d)

4

7.

In a dc machine 6 pole wave winding is used. The number of parallel paths are?

a)

6

b)

4

c)

2

d)

1

8.

In DC machine torque depends on which of the following?

a)

flux (φ)

b)

armature current

c)

speed

d)

Both A and B

9.

Maximum power will be developed when back emf is

a)

equal to supply voltage.

b)

half of the supply voltage

c)

double the supply voltage.

d)

all of the above.

10.

Transformation Ratio K=

a)

N2/N1

b)

V1/V2

c)

I2/I1

d)

M1/M2