Question # 1

In a transformer, the number of primary coil and secondary coil are 5 and 4 respectively. If 240 V is applied on the primary coil, then the ratio of current in primary and secondary coil is:

Choose an answer

4:5

5:4

5:9

9:5

Transformer obeys the law of conservation of:

Choose an answer

Flux

Momentum

Power

emf

Why does a transformer have a core made of iron

Choose an answer

iron has a high melting point

iron is a conductor of head

iron is a conductor of electricity

iron is a magnetic material

A coil having 500 square loops, each of the side 10cm is placed normal to a magnetic field which increased at the rate 1T/sec. The emf induced is:

Choose an answer

0.1V

0.5V

1V

5V

Direction of induced current always:

Choose an answer

Oppose the cause

Remains same as that of cause

equal to cause that produces it

Directs the cause

A transformer is used to light a 100 W, 110 V lamp from a 220V supply. If the supply current is 0.5A, the efficiency of the transformer is:

Choose an answer

30%

50%

80%

90%

The primary winding of a transformer has 500 turns whereas its secondary has 5000 turns The primary is connected to an a.c supply of 20V,50Hz. The secondary will have an output of

Choose an answer

2V, 50Hz

200V, 500Hz

200V, 50Hz

2V, 5Hz

In the step up transformer, when the alternating voltage increase then the alternating current will

Choose an answer

Increase

Decrease

not change

Not depend on core

Frequency of A.C. used in Pakistan is:

Choose an answer

100 CPs

60 CPs

50 CPs

120 CPs

The number of turns in the primary and secondary coils of a transformer are 100 and 300 respectively. If the input power is 60 W then the output power is:

Choose an answer

180 W

3 kW

60 W

90 W

When the power output in watts equals one half the power input, the efficiency of the transformer becomes:

Choose an answer

100%

200%

50%

Zero

In a transformer, the immediate cause of the induced alternating current in the secondary coil is:

Choose an answer

a varying magnetic field

a varying electric field

the iron core of the transformer

a motion of the primary coil

The primary and secondary coils of a transformer are linked

Choose an answer

Electrically

Magnetically

Are not linked at all

When no power is drawn in the secondary coil of an ideal transformer, the power of the primary coil of an ideal transformer, is:

Choose an answer

one

zero

½

∞

A magnet is allowed to fall through a metal ring. Its acceleration A), during the fall is:

Choose an answer

a < g

a > g

a = g

a = 0

The north pole of a bar magnet is rapidly introduced into a solenoid from its end P. Which of the following statements correctly depicts the phenomenon taking place?

Choose an answer

No induced emf is set up.

The end P of the solenoid behaves like a north pole.

None of the above

If the magnetic flux linked with a coil varies at the rate of 1wb/min, the induced emf is:

Choose an answer

1V

1/60V

60V

None of these

The induced current can be increased by:

Choose an answer

Increasing the number of turns of coil

By moving the coil faster through the field

By increasing the strength

All of the above

The motional of emf depends upon the:

Choose an answer

Length of conductor

Strength of magnetic field

Speed of conductor

All the above

In general, in an ac circuit:

Choose an answer

The average value of current is zero

The average value of the square of the current is zero

The average power dissipation is zero

The phase difference between voltage and current is zero

More Classes

Other Links

MDCAT Physics Chapter 9 Electromagnetic Induction Online Test MCQs With Answers

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer

Choose an answer