Practice MCQ Questions and answers on Physics-GK

81

Which tube used to produce X-ray?

A) Coolidge tube B) X-ray tube C) Roentgen D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

Coolidge tube is used to produce X-ray.

82

A Fuse wire is characterised by

A) High resistance and low melting point B) High resistance and high melting point C) Low resistance and high melting point D) Low resistance and low melting point

Discuss

Answer & Solution

Answer: Option A

Solution:

Fuse is a piece of wire of a material with a very low melting point. When a high current flows through the circuit due to overloading or a short circuit, the wires gets heated and melts. As a result,the circuit is broken and current stops flowing.

83

When the main switch of the house is put off it disconnects the

A) Live wire only B) Live wire and the earth wire C) Live wire and the neutral wire D) Earth wire and the neutral wire

Discuss

Answer & Solution

Answer: Option C

Solution:

It disconnects the live and neutral wire.

84

Electric power is measured in units of

A) Volt B) Joule C) Watt D) Ampere

Discuss

Answer & Solution

Answer: Option C

Solution:

Electricity is measured in Watts and kilowatts.

85

Find the current (in A) when a charge of 500 Coulomb flows in 25 seconds.

A) 12500 B) 20 C) 40 D) 6250

Discuss

Answer & Solution

Answer: Option B

Solution:

Current = Charge/Time
I = Q/t
I = 500/25
I = 20 A.

86

What is the value of 1 kW = ?

A) 1000 W B) 10 W C) 100 W D) 10000 W

Discuss

Answer & Solution

Answer: Option A

Solution:

1 kW = 1000 W.

87

The electric current in a metal wire is due to the flow of -

A) Electrons B) Protons C) Ions D) Holes

Discuss

Answer & Solution

Answer: Option A

Solution:

The electric current in a metal wire is due to the flow of electrons.

88

An electric fuse is based on

A) The chemical effect of the current B) The magnetic effect of the current C) The heating effect of the current D) All of the above

Discuss

Answer & Solution

Answer: Option C

Solution:

The electric fuse is based on the heating effect of the current. Electric fuse have low melting point so when high current flow through fuse wire it heated and melted and break down the electric circuit.

89

Metals are good conductors of electricity because

A) The atoms are lightly packed B) They contain free electrons C) They have high melting point D) All the above

Discuss

Answer & Solution

Answer: Option B

Solution:

Metals are an excellent conductor of electricity and heat because the atoms in the metals form a matrix through which outer electrons can move freely. Instead of orbiting their respective atoms, they form a sea of electrons that surround the positive nuclei of the interacting metal ions.

90

Find the current (in A) when a charge of 1200C flows in 6 seconds.

A) 7200 B) 200 C) 100 D) 3600

Discuss

Answer & Solution

Answer: Option B

Solution:

Current = Charge/Time
I = Q/t
I = 1200/6
I = 200 A.