Electromagnetic Induction Test

Result

Electromagnetic Induction Test - 69

Score
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Weekly Quiz Competition

Question 1
4 / -1

To core of a transformer is laminated so that

A
Ratio of voltage in the primary and secondary may be increased

B
usting of the core may be stopped

C
Energy losses due to eddy currents may be reduced

D
Change in flux is increased
Question 2
4 / -1

In transformer, core is made of soft iron to reduce.

A
Hysteresis losses

B
Eddy current losses

C
Force opposing electric current

D
None of the above
Question 3
4 / -1

A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 amp, the efficiency of the transformer is approximately

A
30%

B
50%

C
90%

D
10%

Solution
Question 4
4 / -1

In a transformer 220 ac voltage is increased to 2200 volts. If the number of turns in the secondary are 2000, then the number of turns in the primary will be

A
200

B
100

C
50

D
20

Solution
Question 5
4 / -1

The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an ac supply of 120 V and the current flowing in it is 10 A. The voltage and the current in thesecondary are

A
240 V, 5 A

B
240 V, 10 A

C
60 V, 20 A

D
120 V, 20 A

Solution
Question 6
4 / -1

A transformer is employed to reduce 220 V to 11 V. The primary draws a current of 5 A and the secondary 90 A. The efficiency of the transformer is

A
20%

B
40%

C
70%

D
90%

Solution
Question 7
4 / -1

In a step-up transformer, the turn ratio is 1 : 2. A Leclanche cell (e.m.f. 1.5 V) is connected across the primary. The voltage developed in the secondary wouldbe

A
3.0 V

B
0.75 V

C
1.5 V

D
Zero
Question 8
4 / -1

The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux ϕ linked with the primary coil is given by ϕ = ϕ₀ + 4t, where ϕ is in webers, t is time in seconds and ϕ₀, is a constant, the output voltage across the secondary coil is

A
90 volts

B
120 volts

C
220 volts

D
30 volts

Solution
Question 9
4 / -1

A transformer connected to 220 volt line shows an output of 2 A at 11000 volt. The efficiency is 100%. The current drawn from the line is

A
100 A

B
200 A

C
22 A

D
11 A

Solution
Question 10
4 / -1

A step-up transformer operates on a 230 V line and supplies a load of 2 ampere. The ratio of the primary and secondary windings is 1 : 25. The current in the primary is

A
15 A

B
50 A

C
25 A

D
12.5 A

Solution