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CBSE Questions for Class 8 Physics Some Natural Phenomena Quiz 9 - MCQExams.com
CBSE
Class 8 Physics
Some Natural Phenomena
Quiz 9
An ebonite rod can be charged by touching it with a charged copper rod.
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True
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False
Explanation
An ebonite rod can be charged by not touching it with a charged copper rod, but by induction method.
To find whether a body is charged or not, an uncharged electroscope is used.
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True
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False
Explanation
To find whether a body is charged or not, an uncharged electroscope is used. The charge of the body to be tested is transferred to the leaves of electroscope and they repel each other due to the similar charges on both the leaves.
The electroscope shouldn't be charged already otherwise the pre-existing charge will interfere with our observation and we won't be able to detect the defection in its leaves properly.
To find whether the charge on a body is positive or negative, an uncharged electroscope is used.
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True
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False
Explanation
To find whether a body is charged or not, a charged electroscope is used.
Two objects when rubbed together, get charged. The charges on them are:
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Equal and opposite
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Equal and similar
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Unequal and similar
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Unequal and opposite
Explanation
Two objects when rubbed together get charged. One body losses some electrons and becomes positively charged and the other body gains electrons and becomes negatively charged.
So when two objects rubbed together, get charged. The charges on them are equal and opposite.
When an ebonite rod is rubbed with fur, the rod acquires
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positive charge
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negative charge
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no charge
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none of the above
Explanation
On rubbing the ebonite rod with fur electrons move from fur to the ebonite rod and hence ebonite gets a negative charge.
When a glass rod is rubbed with dry silk cloth, the charge acquired by the silk cloth is
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Positive
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Negative
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Both positive and negative
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none of the above
Explanation
When a glass rod is rubbed with dry silk cloth, the charge acquired by the silk cloth is negative .
What happens when two bodies are rubbed together?
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They get equal charged but the same nature
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They get equal charged but the opposite nature
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Nothing happend with rubbing
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None
Explanation
When two bodies are rubbed together there will be a transfer of electrons from one body to the other body. The body losing electrons acquires a positive charge and the body receiving electrons acquires an equal amount of negative charge.
What are the weak zones around the boundaries of plates underneath Earth, which are prone to slide and cause earthquakes?
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Fault zone
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Eruption zone
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Explosive zone
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Sliding zone
Explanation
Earthquakes are caused by the movement of plates, the boundaries of the plates are the weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.
Where is the lower end of a lightning conductor fixed in the building?
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at the top
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at a window
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at the base
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in the ground
Explanation
A lightning conductor is a device used to protect buildings from the damaging effect of lightning.
Lightning conductor consists of a metallic rod, taller than the building, which is installed in the walls of the building during its construction. One end of the rod is kept out in the air and the other lower end is buried deep in the ground.
Hence, if lightning hits the building, it will strike the rod and be conducted to ground through wire.
An ebonite rod is rubbed with fur. The charge on the ebonite rod is ______ and the charge on the fur is _______.
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Negative, Positive
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Positive, Negative
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Negative, Negative
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Positive, Positive
Explanation
When an ebonite rod is rubbed with fur, it acquires a small charge.
An ebonite rod is rubbed with fur. The charge on the ebonite rod is negative and the charge on the fur is positive.
What is the cause for the streaks of bright light and sound produced during lightning?
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Meeting of positive charges
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Meeting of negative charges
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Meeting of like electric charges
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Meeting of unlike electric charges
During the thunderstorm, ________ move upwards while ________ move downards.
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Water droplets, air currents
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Air currents, charges
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Air currents, water droplets
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Water droplets, charges
Explanation
During the development of a thunderstorm, the air currents move upward while the water droplets move downward, hence option $$C$$ is correct.
Electric charges formed by rubbing are _____.
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moving
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static
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dynamic
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none of these
Explanation
When two bodies rub with each other then electron get transferred from one to other. Body on which charge will accumulate become negative charged . And other will be positively charged. Nature of these charge is static.
Henge charge developed by rubbing is
static
.
Choose the correct option that shows the rod and fur after charging
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0%
0%
0%
Choose whether true or false:-
Earthing prevents shocks in buildings.
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True
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False
Explanation
The earthing is a metal conductor that connects all the electrical appliances and this earthing channelises the leakage current or current induced due to lightning to the earth around the building.
This conductor provides a low resistance path for the electric discharge to flow through and go to ground.
Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current, hence the given statement is true.
Lightning is caused in the atmosphere primarily due to
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Opposite charges accumulation at edges of a cloud.
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Discharge between two similarly charged clouds.
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Discharge between one charged and one neutral cloud.
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None of these
Explanation
Lightning is caused in the atmosphere because o
pposite charges
accumulate at edges of a cloud.Which results in electric discharge between two oppositely charged clouds.
What is a positive charge?
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The charge acquired by a glass rod when it is rubbed with silk
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The charge acquired by silk when it is rubbed with a glass rod
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The charge acquired by plastic straw when it is rubbed with a silk
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None of these
Explanation
It is a convention to call the charge acquired by a glass rod when it is rubbed with silk as positive, hence option $$A$$ is correct.
In an electroscope, if aluminium strips are replaced by plastic strips, and a charged object is touched with the metal top of the electroscope:
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the plastic strips will diverge
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the plastic strips will not diverge
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one strip will move away while other will remain
same.
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the plastic strips will come more closer.
Why is Earthing done in buildings?
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To protect us from electric shocks
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To give extra strength to the building
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To transfer extra current to air
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None of these
Explanation
Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current, hence option $$A$$ is correct.
Tremors or earthquakes on the Earth can also be caused when a volcano erupts, or a meteor hits the Earth or an underground nuclear explosion is carried out.
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True
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False
How does charges separate during a thunderstorm?
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Due to rubbing of air particles
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Due to movement of air
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Due to movement of air current and water droplets
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None of these
Explanation
The rigorous movement of air currents upwards and water droplets downards causes the charges to separate, hence option $$C$$ is correct.
The positive charges are collected at ________ of clouds and the negative charged are collected at ________ of the cloud.
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Upper edges; lower edges
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Lower edges; upper edges
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Lower edges; center
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Upper edge; center
Explanation
The positive charges get collected on the upper edges of the cloud and the negative ones are collected on the lower edges.
Why does air (a poor conductor of eletricity) allows the flow of electrical charges?
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Air becomes a conductor for lightning
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Air is not able to resist the flow of charges when very high charge is accumulated
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The charges get heavily accumulated
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None of these
Explanation
When the magnitude of the accumulated charges becomes very large, the air which is normally a poor conductor of electricity, is no longer able to resist their flow, hence options $$B&C$$ are correct.
The process of electric discharge can't occur between?
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Two or more clouds
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Between clouds and Earth
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Between air and clouds
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None of these
Explanation
The process of electric discharge can not occur between air and clouds as air is a poor conductor.
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