Practice MCQ Questions and answers on Physics-GK

71

Rainbow is produced when sunlight fall on drops of rain. Which of the following physical phenomena are responsible for this?

I.Diffusion
II.Refraction
III.Internal reflection

A) I, II and III B) I and II C) II and III D) I and III

Discuss

Answer & Solution

Answer: Option C

Solution:

Refraction and internal reflection are responsible for this physical phenomena.

72

Natural radioactivity was discovered by

A) Marie Curie B) Ernest Rutherfor C) Henri Becquerel D) Enrico Fermi

Discuss

Answer & Solution

Answer: Option C

Solution:

Natural radioactivity was discovered by Henri Becquerel.

73

Planets are

A) luminous heavenly bodies revolving around a star B) non-luminous heavenly bodies C) luminous heavenly bodies that twinkle D) luminous heavenly bodies that do not twinkle

Discuss

Answer & Solution

Answer: Option B

Solution:

Planets are non-luminous heavenly bodies.

74

One nanometer is equal to

A) 10^-6m B) 10^-8m C) 10^-9m D) 10^-5m

Discuss

Answer & Solution

Answer: Option C

Solution:

One nanometer is equal to 10^-9 m.

75

Mica is used in electrical appliances such as electric iron because mica is

A) a good conductor of heat but a bad conductor of electricity B) a bad conductor of heat but a good conductor of electricity C) a good conductor of heat as well as electricity D) a bad conductor of heat as well as electricity

Discuss

Answer & Solution

Answer: Option A

Solution:

Mica is used in electrical appliances such as electric iron because mica is a good conductor of heat but a bad conductor of electricity.

76

It is easier to roll a barrel full of coal tar than to pull it because

A) the full weight of the barrel comes into play when it is pulled B) the rolling friction is much less than the sliding friction C) more surface area of the barrel is in contact with the road when it is pulled D) coal tar is a liquid and it flows in the barrel when it is rolled

Discuss

Answer & Solution

Answer: Option B

Solution:

When a body slides (moves with all its surface area in contact) over another body, the resistance faced is due to sliding friction. Hence rolling friction is less than the sliding friction. Thus it is easier to roll a barrel full of coal tar than to pull it.

77

Minimum number of unequal vectors which can give zero resultant are

A) two B) three C) four D) more than four

Discuss

Answer & Solution

Answer: Option B

Solution:

The minimum number of vectors of unequal magnitude required to produce zero resultant is three.

78

Intensity of sound has

A) an object existence B) a subject existence C) no existence D) both subjective and objective existence

Discuss

Answer & Solution

Answer: Option A

Solution:

Intensity of sound has an object existence.

79

Rain is falling vertically downwards. To a man running east-wards, the rain will appear to be coming from

A) east B) west C) northeast D) southeast

Discuss

Answer & Solution

Answer: Option A

Solution:

With vertical, the relative velocity will be inclined and appear to be coming from east.So the rain will appear to be coming from east.

80

An aeroplane is flying horizontally with a velocity of 600 km/h and at a height of 1960 m. When it is vertically at a point A on the ground a bomb is released from it. The bomb strikes the ground at point B. The distance AB is

A) 1200 m B) 0.33 km C) 3.33 km D) 33 km

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board