# KVPY (Kishore Vaigyanik Protsahan Yojana) Stream SB-SX (Class 12 & 1st Year B.Sc.) Physics: Questions 143 - 146 of 268

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## Question number: 143

MCQ▾

### Question

The bob of a simple pendulum executes simple harmonic motion in water with a period t, while the period of oscillation of the bob is t0 in air. Neglecting frictional force of water and given that the density of the bob is . What relationship between t and t0 is true?

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 144

MCQ▾

### Question

A water drop of mass m = 80 mg is introduced between two plates with separation d = 0.06 mm. Calculate the force of attraction between the plates.

### Choices

Choice (4) Response

a.

3.11 N

b.

3.0 N

c.

3.87 N

d.

2.17 N

## Question number: 145

» Ray Optics » Reflection and Refraction of Light » Spherical Surface

Appeared in Year: 2014

MCQ▾

### Question

A concave mirror of radius of curvature R has a circular outline of radius r. A circular disc is to be placed normal to the axis at the focus so that it collects all the light that is reflected from the mirror from a beam parallel to the axis. For r < < R, the area of this disc has to be at least,

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 146

MCQ▾

### Question

A long vertical wire carrying current i produces a neutral point with the earth’s magnetic field at 10 cm from the wire. If the horizontal component of the earth’s magnetic field is 0.18 gauss, the current in the wire is –

### Choices

Choice (4) Response

a.

0.50 A

b.

4.5 A

c.

5 A

d.

50 A

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