Practice MCQ Questions and answers on Physics-GK

71

Ohm's law is valid in case of

A) Semiconductor B) Conductor C) Superconductor D) Insulator

Discuss

Answer & Solution

Answer: Option B

Solution:

Ohm's law is valid in case of conductor.

72

Electrical burns occur principally because of

A) Radiation pulses of the electricity B) The heat generated by the flow of electrical current through the body C) The high energy of electrons D) All of the above

Discuss

Answer & Solution

Answer: Option B

Solution:

Electrical burns are among the most serious burns and require immediate medical attention. They occur when electric current flows through tissues or bone, generating heat that causes tissue damage. Arc or flash burns result from high temperatures caused by an electric arc or explosion near the body.

73

The SI unit of resistance is:

A) Newton B) Coulomb C) Ohm D) Joule

Discuss

Answer & Solution

Answer: Option C

Solution:

The SI unit of resistance is Ohm.

74

Electrical Energy is the energy of

A) Protons B) Neutrons C) Electrons D) All the above

Discuss

Answer & Solution

Answer: Option C

Solution:

The SI unit of resistance is electrons.

75

As water is cooled from 4 deg C to 0 deg C, its density

A) Increases B) Decreases C) Remains same D) None of the above

Discuss

Answer & Solution

Answer: Option B

Solution:

When water is cooled from 4°C to 0°C, its density decreases.

76

Fish and other aquatic creatures can live inside a deep frozen pond because

A) Fish are cold-blooded animals B) Ice is a bad conductor of heat C) There will always be water just beneath the ice level D) They can adapt themselves to live in ice

Discuss

Answer & Solution

Answer: Option C

Solution:

All liquids have a boiling point and a freezing point. Underneath the frozen upper layer, the water remains in its liquid form and does not freeze. Also, oxygen is trapped beneath the layer of ice. As a result, fish and other aquatic animals find it possible to live comfortably in the frozen lakes and ponds.

77

The density of a gas is maximum at

A) Low temperature, low pressure B) Low temperature, high pressure C) High temperature, low pressure D) High temperature, high pressure

Discuss

Answer & Solution

Answer: Option B

Solution:

The density of gases depends upon the temperature. The higher the temperature, the more the molecules are spread out and the lower the density.

78

Lakes freeze in cold countries in winter, leaving the water underneath at

A) 0°C B) 0°F C) 4°C D) 4°F

Discuss

Answer & Solution

Answer: Option C

Solution:

Freezing takes place at he top of the lake this is because water colder than 4 degree celsius usually starts to expand and get less dense as it gets colder. It is the liquid with more density that settles at the bottom while the less denser floats above it.

79

A bimetal made copper and iron strips welded together is straight at room temperature. It is held vertically with iron strip towards left and copper strip towards right. If this bimetal is heated, it will

A) Remain straight B) Bend towards right C) Bend towards left D) None of these

Discuss

Answer & Solution

Answer: Option C

Solution:

Since the strips are welded together, the combined strip will bend towards left ( towards iron ) since copper strip will have more length than the iron strip.

80

Thermal expansion of materials arises from

A) Strong bonds B) Thermal vibrations C) Weak bonds D) Asymmetry of potential energy curve

Discuss

Answer & Solution

Answer: Option D

Solution:

Thermal expansion of materials arises from asymmetry of potential energy curve.