Tag: physics

Questions Related to physics

Which one of the following is an insulator?

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

  1. nichrome

  2. graphite

  3. human body

  4. bakelite

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Correct Option: D
Explanation:

Answer is D.

Bakelite, or polyoxybenzylmethylenglycolanhydride, is an early plastic. It is a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde. It was developed by Belgian-born chemist Leo Baekeland in New York in 1907.
One of the first plastics made from synthetic components, Bakelite was used for its electrical nonconductivity and heat-resistant properties in electrical insulators, radio and telephone casings, and such diverse products as kitchenware, jewelry, pipe stems, firearms, and children's toys.
If the Bakelite is dry, it won't conduct electricity, however if it is wet and a high enough voltage is applied to it, it might conduct electricity.

Which one of the following is bad conductor of electricity ?

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

  1. Acid

  2. Coal

  3. Distilled water

  4. Human body

Show answer
Correct Option: C
Explanation:

Distilled water  is bad conductor of electricity.


Distilled water does not contain any dissolve ions which conduct electricity by acting as a carrier of electric charge and hence they do not conduct electricity.

Option C is correct.

Choose the appropriate option:
In metals______ than the insulators. 

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

  1. There are more free electrons

  2. There are less free electrons

  3. There are all free electrons

  4. There are no free electrons

Show answer
Correct Option: A
Explanation:

Metals have electronic configuration such that there is always one, two or three electrons present which lie in the outer most shell and are loosely bounded. Therefore, in metals there are always more free electrons. 

Materials which allow larger currents to flow through them are called :

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

  1. insulators

  2. conductors

  3. semiconductors

  4. alloys

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Correct Option: B
Explanation:

The current does not flow through the insulators. We know that a large amount of current will flow through the conductor due to the presence of free electrons. Relatively small amount of current also flow through semiconductors or some alloys. 

State whether true or false.
Copper is a poor conductor of electricity as compared to glass.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

The given statement is false because copper is not a good conductor of electricity as compared to glass, The reason is that glass is usually an insulator and have electrons held tightly which means they aren't shared between other atoms, so it is a poor conductor of electricity whereas copper is a metal and has free electrons in it and therefore is good conductor of electricity.

State whether true or false.
Pure water is a good conductor of electricity.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

The given statement is false,  because pure water is not a good conductor of electricity. Because water itself isn't a conductor. It i the presence of salts in an impure water that makes it conductive. But in pure water, it has all salts removed from it and therefore, pure water is then devoid of free ions and hence not a good conductor.

State whether the given statement is True or False :

Conductors when charged transfer all charges to the entire surface of the conductor. 

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
True.
When conductors gets charged then all the charge will be distributed to the surface of conductor.

Option A is correct.

Poor conductors of electricity is/are: 

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

  1. Silver

  2. Aluminium

  3. Pure water

  4. Copper

Show answer
Correct Option: C
Explanation:
Pure water is a poor conductor since its molecules do not have free electrons to travel and thus transfer current.

Option C is correct.

In conductors electrons can flow because their

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

  1. ions are free

  2. electrons are free and mobile

  3. protons are free

  4. negative ions are free

Show answer
Correct Option: B
Explanation:

In conductors electrons can flow because their because their electrons are free and mobile.


Option B is correct.

From below which is the example of insulators.

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

  1. Metallic elements

  2. Non Metallic elements

  3. graphite

  4. acqueous solution of salt

Show answer
Correct Option: B
Explanation:

Metallic elements have free electrons on the metallic surface and thus they are extremely good conductors. 


Graphite is a good conductor of electricity because its electrons are delocalized or free to move around. Graphite is structured into planes with tightly bound atoms. There is a great deal of distance between planes, and they are bonded weakly together, allowing the electrons to move around.

When a salt is added in water, it dissociates into respective ions and these collect on the cathode and anodes respectively and a current is maintained. 
Hence it is a conductor.