Tag: some natural phenomena

Questions Related to some natural phenomena

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

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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.

Lightning strikes building when induced charge on top building is too high. This statement is:

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. True

  2. False

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Correct Option: B
Explanation:

Lightning strikes the tallest buildings in order to attain the shortest path for the discharge.

Why are lightning conductors pointed in shape?

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. To reduce mass.

  2. It attracts more electric charge due to very small radius and hence surface area.

  3. It allows more current.

  4. It repels the incident lightning discharge.

Show answer
Correct Option: B
Explanation:

Pointed lightning conductors attract more charge because of small cross sectional area. Surface density of charge is hence increased considerably.

A lightning conductor consists of

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. several sharp metal spiked connected to a thick copper strip.

  2. a metal plate buried deep inside the ground connected to the ground end of copper strip.

  3. a conductor fixed on top of the building.

  4. all of the above

Show answer
Correct Option: D
Explanation:

A lightning conductor consists of a conductor fixed on top of the building. The conductor consists of several sharp metal spikes connected to a thick copper strip. The other end of the copper strip is fixed to a metal plate buried deep inside the ground. 

The lightning conductor used in building, protects the building by :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. dissipating the electric charge away from the building

  2. conducting the lightning safely to the ground

  3. absorbing the electric charge

  4. None of these

Show answer
Correct Option: B
Explanation:

The lightning conductor used in building, protects the building by conducting the lightning safely to the ground.


Option B is correct.

Which of the following correctly represents the sequence of operations of isolator circuit breaker and earthing switch while opening a circuit :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. close earthing switch - open circuit breaker open isolator

  2. open isolator - close circuit breaker - open earthing switch

  3. open circuit breaker - open isolator - close earthing switch

  4. close circuit breaker - close isolator - open earthing switch

Show answer
Correct Option: C
Explanation:

Open circuit breaker - open isolator - close earthing switch represents the sequence of operations of isolator circuit breaker and earthing switch while opening a circuit.


Option C is correct.

What is the main function of lightning conductor?

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. To capture lightning stroke and conduct discharge current safely to the ground

  2. To capture lightning stroke and conduct discharge current safely to the cloud

  3. To capture lightning stroke and conduct discharge current safely to the building

  4. None

Show answer
Correct Option: A
Explanation:

A lightning rod conducts a positive charge up to meet the negative charge of a lightning strike, allowing the strike to hit the rod and travel through attached wires to an underground connection. This diverts the strike away from a building, preventing or lessening potential damage.


Option A is correct.


Which of the following correctly presents the sequence of operations of isolator circuit breaker and earthing switch while closing a circuit :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. Ensure circuit breaker is closed - close isolator - open earthing switch

  2. Ensure circuit breaker is open - close isolator - open earthing switch if any close circuit breaker

  3. Ensure circuit breaker is open - open isolator - open earthing switch if any close circuit breaker

  4. None of the above

Show answer
Correct Option: B
Explanation:

 Ensure circuit breaker is open - close isolator - open earthing switch if any close circuit breaker .


Option B is correct.

An ordinary tube light used for lighting purposes contains :

physics some natural phenomena lightning conductors lightning safety advanced of lightning

  1. fluorescent material and an inert gas

  2. one filament, reflective material and mercury vapour

  3. fluorescent material and mercury vapour

  4. two filaments, fluorescent material and mercury vapour

Show answer
Correct Option: D
Explanation:

An ordinary tube light used for lighting purposes contains:

1. Two filaments
2. Mercury vapours
3. Fluorescent material

Option D is correct.