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Questions Related to physics

Semiconductors those are created by doping an intrinsic semiconductor with donor impurities are

intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. p-type

  2. n-type

  3. may be any of them

  4. none of them

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Correct Option: B
Explanation:

Donor impurities are the ones that donate electrons to the semiconductor atom. For each donor atom added, there is one electron donated to the semiconductor atom. As a result, the electrons in such type of semiconductors are majority charge carriers. Therefore, this extrinsic semiconductor formed by adding donor impurities are called n-type semiconductors.

Transistors (devices that enable current switching) make use of

intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. Intrinsic semiconductor

  2. Extrinsic semiconductor

  3. both of them

  4. none of them

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Correct Option: B
Explanation:

A transistor is a device which consists of a thin layer of one type of extrinsic semiconductor sandwiched between two thick layers of other types of extrinsic semiconductor. There are two types of transistors:

  1. pnp transistor and,
  2. npn transistor
    So, a transistor is made of extrinsic semiconductor.

 A semiconductor diode (devices that allow current in only one direction) consists of 

intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. Intrinsic semiconductor

  2. Extrinsic semiconductor

  3. both of them

  4. none of them

Show answer
Correct Option: B
Explanation:

A semiconductor diode consists of p-n junction having metallic contacts at both the ends. A single piece of a semiconductor material (either Si or Ge) with one portion doped with a pentavalent impurity and other portion doped with trivalent impurity behaves as a p-n junction. Means, extrinsic semiconductor or semiconductor doped with impurities of both p and n are used in p-n junction diode.

The impurity atoms with which pure silicon should be doped to make a p - type semiconductor are those of :

intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. phosphorus

  2. antimony

  3. boron

  4. aluminium

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Correct Option: C,D
Explanation:

p type semiconductor has more number of holes than electrons.
P-type semiconductors are created by doping an intrinsic semiconductor with acceptor impurities like boron, aluminium and other group IIIA elements

Why is a car or a bus safe place during lightening?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Because it does not rain inside the bus.

  2. Because lightening cannot travel through the glass.

  3. Because a car or a bus is insulated from the Earth.

  4. None of the above.

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Correct Option: C
Explanation:

A car or a bus stand on rubber tyres. Rubber being an insulator, the body of car / bus stays separated or insulated from the Earth. So, it does not attract lightening. If we take shelter in a car / bus during lightening, there is no chance to be hit by the lightening.

During lightning it is safer to_______?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Take shelter under short trees

  2. Take shelter under tall trees

  3. Carry umbrella open

  4. Stand in open fileds

Show answer
Correct Option: A
Explanation:

It is safe to take shelter under short tress when you have no option, Lightning mostly gets attracted by tall targets.

When you are in open field or open area and do not have any safe places to hide during thunderstorm what should be done?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Make yourself smallest target.

  2. Squat low on the ground.

  3. Place your hands on your knees with head between the hands.

  4. All of the above.

Show answer
Correct Option: D
Explanation:

During lightning make yourself smallest target by squat low on the ground and hands on your knees with your head between the hands. This is safe position.

Which of the following will not cause any harm to us during thunderstorm?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Using phones with cord.

  2. Switching off electric light.

  3. Plugging in electrical appliances.

  4. All will cause harm.

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Correct Option: B
Explanation:

During lightning switching off of electric lights does not cause any harm to us. Using phones with cord and plugging in electrical appliances may prove dangerous due to short circuiting  if a thunder strikes nearby.

Which of the following is permissible during a thunderstorm?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Using a telephone having cord

  2. Using a mobile phone

  3. Taking a bath under running water

  4. Standing under a tree

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Correct Option: B
Explanation:

It is safe to use mobile phones or cordless phones as there are no chance of electric shock due to lightning or thunder.

What should be the length of the metal rod used as lightning conductor?

physics some natural phenomena safety from lightning lightning safety advanced of lightning

  1. Shorter than the walls of the building.

  2. Same length or equals.

  3. Taller than the walls of the building.

  4. Nothing specific, can be of any length.

Show answer
Correct Option: C
Explanation:

The lightning conductor should be taller than the walls of the building because lightning gets attracted to the taller targets.