Electromagnetic Induction & Alternating Currents-AC Generator and Transformer (NEET Physics): Questions 6 - 9 of 13

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Question number: 6

» Electromagnetic Induction & Alternating Currents » AC Generator and Transformer

MCQ▾

Question

Large transformer, when used for some time, become hot and are cooled by circulating oil. The heating of transformer is due to

(1) Heating effect of current

(2) Hysteresis loss

(3) Chemical effect of current

(4) Magnetic effect of current

Select the correct answers and mark it according to the following

Choices

Choice (4) Response

a.

1, 2 and 3 are correct

b.

2 and 4 are correct

c.

1 and 2 are correct

d.

1 and 3 are correct

Question number: 7

» Electromagnetic Induction & Alternating Currents » AC Generator and Transformer

Assertion-Reason▾

Assertion (Ꭺ)

An electric motor will have maximum efficiency when back e. m. f. is equal to half of the applied e. m. f.

Reason (Ꭱ)

Efficiency of electric motor depends only on magnitude of back e. m. f.

Choices

Choice (4) Response

a.

Both Ꭺ and Ꭱ are false

b.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

c.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

d.

Ꭺ is true but Ꭱ is false

Question number: 8

» Electromagnetic Induction & Alternating Currents » AC Generator and Transformer

MCQ▾

Question

A step-down transformer is used on a 1000 V line to deliver 20 A at 120 V at the secondary coil. If the efficiency of the transformer is 80%, the current drawn from the line is:

Choices

Choice (4) Response

a.

3 A

b.

2.4 A

c.

30 A

d.

0.3 A

Question number: 9

» Electromagnetic Induction & Alternating Currents » AC Generator and Transformer

MCQ▾

Question

The current in the primary coil of a transformer (assuming no power loss) as shown in fig. will be –

Transformer consist of two coils

Transformer Consist of Two Coils

In figure two coils transformer is shown with 220 Ω resistor. Vp is the primary coil voltage and VC is the secondary coil voltage.

Choices

Choice (4) Response

a.

10 -6 A

b.

1.0A

c.

0.01 A

d.

0.1 A

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