# NEET Physics: Questions 691 - 694 of 2142

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## Question number: 691

MCQ▾

### Question

The velocities of three particles of masses 10g, 10g and 30g are 10i, 10j and 10k respectively. The velocity of the center of mass of the three particles is

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 692

Assertion-Reason▾

### Assertion (Ꭺ)

Soft iron is used as a core of transformer.

### Reason (Ꭱ)

Area of hysteresis loop for soft iron is small.

### Choices

Choice (4) Response

a.

Both Ꭺ and Ꭱ are false

b.

Ꭺ is true but Ꭱ is false

c.

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

d.

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

## Question number: 693

MCQ▾

### Question

A closed coil of copper whose area is lm × lm is free to rotate about an axis. The coil is placed perpendicular to a magnetic field of 0.10 Wb/m 2. It is rotated through 180° in 0.01 second. Then (The resistance of the coil is 2.0Ω)

(1) The induced e. m. f. in the coil is 20 V

(2) The induced current in the coil is 10 A

(3) The induced e. m. f. in the coil is 10 V

(4) The induced current in the coil is 20 A

Select the correct answers and mark it according to the following codes:

### Choices

Choice (4) Response

a.

1 and 2 are correct

b.

2 and 4 are correct

c.

1 and 3 are correct

d.

1, 2 and 3 are correct

## Question number: 694

Assertion-Reason▾

### Assertion (Ꭺ)

Lenz’s law violates the principle of conservation of energy.

### Reason (Ꭱ)

Induced e. m. f. opposes the change in magnetic flux responsible for its production.

### Choices

Choice (4) Response

a.

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

b.

Ꭺ is true but Ꭱ is false

c.

Ꭺ is false but Ꭱ is true

d.

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

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