Tag: electric charges and fields

Questions Related to electric charges and fields

Mica is a ____ conductor of electricity.

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. good

  2. bad

  3. positive

  4. None of the above

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Correct Option: B
Explanation:

The electrical and thermal conduction properties of a material can be similar or very different, in metals the electrical and thermal conductivity is due to free electrons, in non-metals thermal conductivity has nothing to do with free electrons, but more to do with lattice vibrations (that is, phonons). 
So mica has good thermal conductivity due to phonons, but doesn't have sufficient free electrons and a very high resistance to be a good conductor of electricity.
Hence, Mica is a poor or bad conductor of electricity.

Why is electrical wiring usually covered with a layer of plastic?

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. To make it strong

  2. To help electricity flow in it

  3. To make it safe

  4. To make it beautiful

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Correct Option: C
Explanation:

Plastic is a good insulator of electricity and makes it possible to work with wires without any harm or injury.

Which of the following is an electrical conductor?

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. Silver

  2. Rubber Cork

  3. Silver-coloured plastic sheet

  4. Wood

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Correct Option: A
Explanation:

Metals are good conductors of electricity.
Silver is a metal and a good conductor of electricity.

Which of the following is an electrical insulator :

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. Aluminium

  2. Gold

  3. Rubber

  4. None of these

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Correct Option: C
Explanation:

Metals are generally good conductors of electricity. So, Gold and Aluminium are good conductors of electricity. 
Non-metals are poor conductors of electricity.
So rubber, being a non-metal, is an electrical insulator and hence a poor conductor of electricity.

Bulb does not glow when the probs are hanged in air. The reason is:

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. air absorbs the electricity

  2. air is a bad conductor of electricity

  3. electricity is discharged into air

  4. air disperses the electricity

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Correct Option: B
Explanation:

For bulb to glow there should be current passing through it's entire circuit. But when probs are hanged in the air the circuit breaks as air do not conduct electricity (or bad conductor of electricity). 

Metals are good conductors because

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. Outer electrons are strongly bound to the atom.

  2. Outer electrons are loosely bound to the atom.

  3. Inner electrons are loosely bound to the atoms.

  4. Protons can detach from the nucleus and conduct electricity.

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Correct Option: B
Explanation:

Metals have loosely bound outer electrons that is they have charge carriers which can move easily (current) when a potential difference is applied. Therefore, these loosely bound outer electrons make metals good conductors. 

Which of the following is an insulator?

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. Wood

  2. Iron

  3. Carbon

  4. Silver

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Correct Option: A
Explanation:

Iron and Silver are metals so they are conductors. While carbon is conductor in graphite and insulator in diamond form. So only option left is wood which an insulator.  

Why is electrical wiring usually made from copper and not silver?

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. Copper is a better conductor

  2. Copper is a better insulator

  3. Copper is less expensive

  4. Copper is non magnetic

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Correct Option: C
Explanation:

Silver is a better conductor, non magnetic but expensive material compared to copper therefore copper is generally used for electrical wiring.

An electrolyte is :

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. a cell

  2. a metal

  3. a liquid that conducts electricity

  4. sugar

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Correct Option: C
Explanation:
Answer is C.
An Electrolyte is a substance that dissociates into ions in solution and acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, and phosphate are examples of electrolytes, informally known as lytes. 
Therefore, it a liquid that conducts electricity.

Some materials have electrons that are tightly bound to the nucleus and are not free to travel within the substance. These materials are called .............

physics electric charges and fields conductors and insulators introduction to electrostatics electricity

  1. conductors

  2. insulators

  3. semiconductors

  4. none of these

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Correct Option: B
Explanation:

Some materials have electrons that are tightly bound to the nucleus and are not free to travel within the substance. These materials are called insulators.
An electrical insulator is a material whose internal electric charges do not flow freely, and therefore make it very hard to conduct an electric current under the influence of an electric field.