Tag: physics

Questions Related to physics

What is earthing?

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. Passage of large electric current resulting from a lightning into the earth

  2. Burying electric charge into the earth

  3. Preventing electric charge from entering the earth

  4. None of the above

Show answer
Correct Option: A
Explanation:

A lightning conductor a device used to prevent tall buildings from being struck by lightning. It is fixed on the top of tall buildings with one end at the top having several sharp metal spikes that attract lightning. This is connected to a copper strip. The other end of the strip is attached to a large metal plate buried deep into the ground causing the electric charge to flow into the earth. This process is called earthing.


Two types of earthings are provided: (a) Equipment earthing and (b) Neutral point earthing. Equipment earthing is provided for

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. Safety of human being

  2. Safety of equipments

  3. Safety of starters and cables

  4. None

Show answer
Correct Option: A
Explanation:

Equipment earthing is a connection done through a metal link between the body of any electrical appliance, or neutral point, as the case may be, to the deeper ground soil. The metal link is normally of MS flat, CI flat, GI wire which should be penetrated to the ground earth grid.

  • Safety of personnel
  • Safety of equipment Prevent or at least minimize damage to equipment as a result of flow of heavy currents.
  • Improvement of the reliability of the power system

Option A is correct.

A lightning conductor installed in a building

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. does not allow the lightning to fall on the building

  2. repels the lightning

  3. forces the lightning to fall in an area where there are no buildings

  4. conducts electric charge to the ground when lightning strikes the building

Show answer
Correct Option: D
Explanation:

A lightning conductor is generally made of metal spikes , which are connected to ground through a copper wire . The spikes are pointed , hence electric field strength is strong around pointed spikes . Due to this intense electric field , spikes conduct electric charge easily to the ground when lightning strikes he building .

Lightning conductor is made up of conducting materials.

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

The lightening conductor is made of conducting material such as copper or aluminium. so, the given statement is true. 

Electric field in the region is given as $E=(10-5x)i$. A charge of the mass 5 kg and charge Q (=1 C) is situated at origin and free to move in given electric field, then choose the correct option (neglect gravity).

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. motion of charge particle is oscillatory

  2. maximum displacement of charge particle from origin is 4 SI units

  3. maximum velocity gain by charge particle is 2 SI units

  4. the position of charge particle, when velocity gained by particle is maximum is 2 SI units

Show answer
Correct Option: D

Lightning conductors are used to save the building from earthquakes.

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Lightning conductors are metallic conductors which acts as a path for flow of current that is discharged through lightning strike.


  Hence, lightning conductors save buildings from lightning strike.

Given statement is $False$.

Where $K & C$ are positive constants and $t$ is time, is applied perpendicular to the plane of a circular loops of radius a and resistance $R$. The total charge that will pass through any point of the loop by the time $B$ becoms zero is:

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. $C \pi a^2/ R K$

  2. $K \pi a^2/R$

  3. $C \pi a^2/R$

  4. None of these

Show answer
Correct Option: C

The electric charge for electrode deposition of one gram equivalent of a substance is :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. one amp/sec

  2. 96,500 /sec

  3. one amp / hour

  4. 96,500 C

Show answer
Correct Option: A

The positive terminal of 12 V battery is connected to the ground. Then the negative terminal will be at :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. -6 V

  2. +12 V

  3. zero

  4. -12 V

Show answer
Correct Option: D
Explanation:

When negative terminal of battery is grounded, positive terminal of battery is at $+12  V$ . When positive terminal is grounded, the negative terminal will be at $-12  V$.

Buildings are more susceptible to a lightning strike because

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. they are higher than their surroundings.

  2. roofs of buildings are wet in rainy season and hence become good conductors of electricity.

  3. the top of the building is wet and acquires an opposite charge to a cloud passing over the top by induction.

  4. All of the above.

Show answer
Correct Option: D
Explanation:

Buildings are highly susceptible to a lightning strike because of the following reasons:

1. They are higher than their surroundings and closer to the clouds.
2. The roofs of buildings are wet in rainy season and hence become good conductors of electricity.
3. The top of the building is wet and acquires an opposite charge to a cloud passing over the top by induction.