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Types of charges and their interaction - class-VIII

Description: types of charges and their interaction
Number of Questions: 23
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Tags: physics analysis of natural phenomena static electricity some natural phenomena
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Which of the following cannot be charged easily by friction?

  1. A plastic scale

  2. A copper rod

  3. An inflated balloon

  4. A woollen cloth


Correct Option: B
Explanation:

Copper rod cannot be charged easily by friction because it is a conductor. Only non-conducting materials can be charged easily by friction.

When a glass rod is rubbed with a piece of silk cloth the rod:

  1. and the cloth both acquire positive charge.

  2. becomes positively charged while the cloth has a negative charge.

  3. and the cloth both acquire negative charge.

  4. becomes negatively charged while the cloth has a positive charge.


Correct Option: B
Explanation:
The two objects charged by friction gets oppositely charged. 
Charge acquired by the glass rod is positive and charge acquired by the cloth is negative. 

When body losses electrons it acquires:

  1. positive charge

  2. negative charge

  3. partially positive charge

  4. partially negative charge


Correct Option: A
Explanation:

When body losses electrons, it becomes electron deficient and acquires positive charge.

When a body gains electrons it acquires

  1. positive charge

  2. negative charge

  3. partially positive charge

  4. partially negative charge


Correct Option: B
Explanation:

When body gains electrons it gets negatively charged.

The device, which can be used to detect whether an object is charged, is:

  1. telescope

  2. microscope

  3. electroscope

  4. none of the above


Correct Option: C
Explanation:

Electroscope is a device that is used for detection and identification of charges on objects.

When two bodies are charged by rubbing they acquire:

  1. equal and opposite charge

  2. equal and same charge

  3. negative charge

  4. positive charge


Correct Option: A
Explanation:

When two bodies are rubbed on one another, they acquire charges equal in amount and opposite in nature.

When two positively charged materials will be placed close together:

  1. both will repel each other.

  2. both will become negative.

  3. both will attract each other.

  4. no interaction / change will be observed.


Correct Option: A
Explanation:

Same charges repel while opposites charges attract each other when placed together.

The objects which acquires small electric charges, when rubbed with each other, are called:

  1. electric objects

  2. charged objects

  3. neutral objects

  4. none of the above


Correct Option: B
Explanation:

In the process of rubbing objects with one another, both acquire small electric charges. These objects are called charged objects.

Rub an empty ball pen refill on a polythene sheet and hold it on top of small pieces of paper. What will be your observation?

  1. Pieces of paper are attracted.

  2. Pieces of paper are repelled.

  3. Pieces of paper are neither attracted nor repelled.

  4. Pieces of paper are either attracted or repelled.


Correct Option: A
Explanation:

When refill is rubbed on polythene it acquires small electric charges. Due to presence of these charges, pieces of paper gets attracted.

What is the frictional order of the following materials on rubbing:

ebonite, glass rod, wool, plastic

  1. Wool, glass rod, ebonite, plastic

  2. Glass rod, wool, plastic, ebonite

  3. Wool, glass rod, plastic, ebonite

  4. Glass rod, wool, ebonite, plastic


Correct Option: D
Explanation:

When any of these materials are rubbed together, the one in higher order gets positive charge (+) and the one in the lower order gets negative charge (-). The correct frictional order is: glass, wool, ebonite and plastic.

What kind of electric charge is acquired on a glass rod when it is rubbed with silk cloth?

  1. Positive charge

  2. Negative charge

  3. Partially positive charge

  4. Partially negative charge


Correct Option: A
Explanation:

By convention, glass acquire higher order than silk as losses electron. So, on rubbing, glass acquires positive charge and silk acquires negative charge.

When a plastic rod is rubbed with the fur, what charge does the plastic rod get?

  1. Positive

  2. Negative

  3. Neutral

  4. None of the above


Correct Option: B
Explanation:

Plastic comes below fur in the frictional series of electric charges. So, fur will get positive charge and plastic rod will get the negative charge.

When an object is rubbed by another, the objects get charged - one as positive and another as negative. In electrostatic series:

  1. the one being positively charged comes first.

  2. the one being negatively charged comes first.

  3. both the objects come together.

  4. objects appear as per their atomic numbers.


Correct Option: A
Explanation:

When two bodies are rubbed for charging, the one acquiring positive charge comes first, on a higher position, in electrostatic series. From the series, it may be interpreted that if two objects are rubbed with each other, the one coming higher in the series will acquire positive charge and the other coming lower in the series will acquire negative charge.

State whether the given statement is True or False :

Depending on which material it is rubbed with, most of the objects can acquire both positive and negative charges in different occasions.

  1. True

  2. False


Correct Option: B
Explanation:

For most of the materials, if those are rubbed with materials occurring higher in electrostatic series, will acquire negative charge. And if those materials are rubbed with materials occurring lower in electrostatic series, will acquire positive charge. Dry human skin, occurring at top of the electrostatic series will always acquire positive charge. Teflon, occurring at the bottom of the electrostatic series will always acquire negative charge.

If we rub our dry forearm with a silk cloth, the hairs on the forearm will stand straight. This is because:

  1. of the attraction force between the hairs and the cloth.

  2. of the charge acquired to the forearm due to rubbing.

  3. of the magnetic field created due to rubbing.

  4. none of the above.


Correct Option: B
Explanation:

When the forearm is rubbed with a cloth of silk, the dry forearm acquires positive charge. So, all the hairs there acquire same positive charge and repel each other. Thus the hairs stand straight after rubbing.

The electrical charges generated by rubbing are:

  1. dynamic

  2. static

  3. neutral

  4. none of the above


Correct Option: B
Explanation:

Static charges are generated by rubbing or friction.

What happens when charged glass rod is brought near a charged plastic straw when rubbed with silk?

  1. Repulsion is observed.

  2. Attraction is observed.

  3. No reaction is observed.

  4. None of the above is observed.


Correct Option: B
Explanation:

When rubbed with silk, glass and plastic acquire opposite charges. So, the glass rod and the plastic straw, after being rubbed by silk, will attract each other.

Inflate two balloons. Hang them in such a way that they do not touch each other. Rub both balloons with woollen cloth and release them. Then:

  1. both balloons attract each other.

  2. both balloons repel each other.

  3. both balloons remain at same position.

  4. none of the above happens.


Correct Option: B
Explanation:

The balloons will be seen to repel each other as both are charged with same polarity.

What happens when a used plastic refill is rubbed with polythene?

  1. Only refill gets charged.

  2. Refill and polythene gets charged.

  3. Only polythene gets charged.

  4. Both gets discharged.


Correct Option: B
Explanation:

Both of them, refill as well as polythene, gets charged by friction.

When a person combs his hair static electricity is sometimes generated by:

  1. friction between comb and hair resulting in flow of electrons.

  2. induction between comb and hair.

  3. conducting property of hair.

  4. contact between comb and hair resulting in a charge.


Correct Option: A
Explanation:

Static electricity, while combing dry hair, is generated by friction between comb and dry hair.

When charges move, they constitute:

  1. energy

  2. light

  3. power

  4. electric current


Correct Option: D
Explanation:

Moving charges constitute electric current.

Rub a glass tumbler with wool. Bring an inflated charged balloon, rubbed with wool, near refill. Then

  1. both balloon and tumbler will repel each other.

  2. both balloon and tumbler attract each other.

  3. no reaction will be observed.

  4. the balloon will burst.


Correct Option: B
Explanation:

When rubbed by wool, glass becomes positive and rubber becomes negative. Opposite charges attract. So, the balloon and the glass tumbler will attract each other.

The atmosphere is held to the earth by _______

  1. gravity

  2. clouds

  3. electric force

  4. friction


Correct Option: A
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