Physics Model Question Paper 4: (For Class 11 and 12 and Pre-Medical/Engineering Entrance)

1.

An unpolarised beam of intensity I₀ falls on a polaroid. The intensity of the emergent light is

(A)

(B) I₀

(C)

(D) zero

Answer: (A)

2.

Blue colour of sea water is due to

(A) interference of sunlight reflected from the water surface

(B) scattering of sunlight by the water molecules

(C) image of sky in water

(D) refraction of sunlight

Answer: (B)

3.

Critical angle for certain medium is Sin^-1 (0.6). The polarizing angle of that medium is ______.

(A) Tan^-1 (1.6667)

(B) Tan^-1 [0.6667]

(C) Tan^-1 [1.5]

(D) s1n^-1[0.8]

Answer: (A)

4.

Dimensional formula for the universal gravitational constant G is

(A) M ^-1 L² T^-2

(B) M⁰ L⁰ T⁰

(C) M ^-1 L³ T^-2

(D) M ^-1 L³ T^-1

Answer: (C)

5.

Electromagnetic wave consists of periodically oscillating electric and magnetic vectors ______.

(A) in randomly oriented planes but vibrating in phase.

(B) in mutually perpendicular planes but vibrating in phase.

(C) in mutually perpendicular planes but vibrating with a phase difference of p

(D) in mutually perpendicular planes but vibrating with a phase difference of p/f

Answer: (B)

6.

For a series LCR circuit at resonance, the statement which is not true is

(A) Peak energy stored by a capacitor = peak energy stored by an inductor

(B) Average power = apparent power

(C) Wattless current is zero

(D) Power factor is zero

Answer: (D)

7.

Hot water cools from 60°C to 50°C in the first 10 minutes and to 42°C in the next 10 minutes. Then the temperature of the surroundings is _____.

(A) 15°C

(B) 10°C

(C) 20°C

(D) 30°C

Answer: (B)

8.

How many 6mF, 200 V condensers are needed to make a condenser of 18 pF, 600 V?

(A) 9

(B) 18

(C) 3

(D) 27

Answer: (D)

9.

How many times more intense is a 60 dB sound than a 30 dB sound?

(A) 1000

(B) 2

(C) 100

(D) 4

Answer: (A)

10.

Hydrogen atom does not emit X-rays because

(A) it contains only a single electron

(B) energy levels in it are far apart

(C) its size is very small

(D) energy levels in it are very close to each other

Answer: (D)