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CBSE Questions for Class 8 Physics Some Natural Phenomena Quiz 3 - MCQExams.com
CBSE
Class 8 Physics
Some Natural Phenomena
Quiz 3
When body losses electrons it acquires:
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positive charge
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negative charge
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partially positive charge
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partially negative charge
Explanation
Electrons itself is a negatively charged particle. When body losses electrons, it becomes electron deficient and acquires positive charge.
When a charge passes from a charged object to earth, the process is called:
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Earthing
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Lightning
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Electroscope
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None of these
Explanation
The process of transferring charge from a charged object to the earth is called earthing.
An electroscope is a device used to detect whether a body is charged or not.
The process of an electric discharge between clouds and the earth or between different clouds causes lightning.
What will be the nature of charge on the uncharged aluminium foil strip of electroscope when a negatively charged body is brought in contact with it?
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Positive
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Neutral
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Negative
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Unpredictable
Explanation
The nature of charge on the foil strip, when a negatively charged body is brought in contact to it, will be negative. Due to conduction, the negative charge of the body is transferred to the uncharged aluminium foil.
When a neutral body is charged by bringing it near to the charged body, the process is called :
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charging by conduction.
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charging by induction.
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charging by rubbing.
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all of the above.
Explanation
When a charged body is brought near, but not in contact, of an uncharged body, the later gets oppositely charged. This method is called charging by induction.
What will be the nature of charge on the metal paper clip of electroscope when a positively charged body is brought in contact with it?
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Positive
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Negative
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Partially negative
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None of the above
Explanation
In a given activity, one positively charged body is coming in contact with uncharged metal paper clip. in this process, positive charge will transfer from charged body to metal paper clip by conduction.
The nature of charge on the object can be detected by:
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Microscope
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Electroscope
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Electrometer
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Telescope
Explanation
A pre-charged electroscope detects the nature of charge on a charged body.
The process of transferring of charge from a charged object to the Earth is called:
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lightning
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thundering
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earthing
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all of the above
Explanation
When a charged object comes in contact with the Earth, the charges flow into the Earth and the body gets discharged. This process is called earthing.
When a foil strips get touched by your hand, it loses charge to the Earth through your body. This process is also referred to as ________.
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earthing
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discharging
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both A and B
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none of the above
Explanation
When we touch the strips, the charges get discharged through our body to the Earth and this process is known as earthing.
_________ is commonly used to make a lightning conductor.
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Carbon
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Copper
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Sodium
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None of the above
Explanation
Copper is a good conductor of electricity and is easily available. Hence it is chosen to make a lightning conductor.
Which of the following is permissible during a thunderstorm?
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Using a telephone having cord
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Using a mobile phone
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Taking a bath under running water
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Standing under a tree
Explanation
It is safe to use mobile phones or cordless phones as there is no chance of electric shock due to lightning during thunder-storm.
Lightning can strike telephone cords, electrical wires, and metal pipes, so, contact with these should be avoided. It is also dangerous to stand under a tree, as it can be uprooted during a thunderstorm.
The device that is used to protect buildings from the effects of lightning is:
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transformer
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transducer
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electrode
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lightning conductor
Explanation
When a building is hit by lightning, the lightning conductor conducts all charges straight into the Earth thus protecting the building from damage.
Why to squat low on the ground during thunderstorm?
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You dont have any safe place
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To make yourself smallest target
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Your in open field
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All of the above
Explanation
When you dont have any safe places or you might be in open area then it is better to make yourself to smallest target for lightning & do not lie on ground.
In the process of earthing, how does charges get discharged to Earth?
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Through some conductor
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Directly to the Earth
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Through transformer
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None of the above
Explanation
Earthing is important for the protection of human life as well as property. For discharging of charges to the Earth some conductor is required, so that electric charges gets conducted into the Earth.
Why earthing is important?
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To protect us from electrical shocks.
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Transfers charge from a charged body to the Earth.
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Both A and B.
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Neither A nor B.
Explanation
Earthing is used to protect you from an electric shock. It does this by providing a path (a protective conductor) for excess charge to flow to earth.
Earthing is the process of transferring charges to the Earth. During lightning, if earthing is not proper, we will get electrical shocks if lightning strikes because that excess charge due to lightning will not be able to go to ground and will cause an electric shock.
When you are in open field or open area and do not have any safe places to hide during thunderstorm what should be done?
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Make yourself smallest target.
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Squat low on the ground.
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Place your hands on your knees with head between the hands.
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All of the above.
Explanation
During lightning make yourself the smallest target by squat low on the ground and hands on your knees with your head between the hands. This is a safe position.
Why bathing is avoided during thunderstorm?
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To avoid contact with electric wires
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To avoid contact with water
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To avoid contact with running water
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All of the above
Explanation
During lightning contact with any such things or material which can carry charges are avoided. There might be chances that electric charge get leaked into water pipeline.
Which of the following will not cause any harm to us during thunderstorm?
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Using phones with cord.
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Switching off electric light.
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Plugging in electrical appliances.
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All will cause harm.
Explanation
During the lthunderstorm, switching off electric lights does not cause any harm to us. Using phones with cords and plugging in electrical appliances may prove dangerous due to short-circuiting if thunder strikes nearby.
What should be the length of the metal rod used as lightning conductor?
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Shorter than the walls of the building.
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Same length or equals.
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Taller than the walls of the building.
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Nothing specific, can be of any length.
Explanation
Lightning conductors can protect buildings from the effects of lightning. A metallic rod, taller than the building, 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 is buried deep in the ground. The rod provides an easy route for the transfer of electric charge to the ground.
________ is the indication to rush for safer place.
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Thunder
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Rain
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Clouds
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All of the above
Explanation
Hearing thunder is an alert to rush to a safer place. It could be dangerous to be out during thunderstorm as there is a possibility of lightning strikes during thunderstorms.
During lightning which of the following is not a safe place?
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In car
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Bus stop
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Inside a house
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Open field
Explanation
Lightning gets attracted towards the tallest target, on open field you will be the tallest target as compared to surroundings so it is a dangerous place for you.
If you are travelling by car during thunderstorm which place is safe?
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Under a tree
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Near street light
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Elevated places
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None of the above
Explanation
It is better to remain in the car, as it provides earthing to charges without harming us. The metal body of the car conducts the charges to the earth without letting it enter our body.
The chances of lightning striking a high-rise object are more. So we should never stand near a tower, a building, or a tree, etc.
Why it is not recommended to touch water metal-pipe lines, electric wires during thunderstorm?
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They are good conductors thus may carry charges.
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They are insulators and never carry charges.
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They may store charges.
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This is a myth.
Explanation
Metal pipe-lines for carrying water and electrical wires are good conductors and carry charges. If a lightning strikes the building, there may be chance of electric shocks getting spread through those due to leakage and this could be dangerous for life.
During lightning, the _______ provides an easy route for the transfer of _______ charges to the ground.
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Metallic rod, only positive
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Plastic rod, only negative
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Metallic rod, electric
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Plastic rod, electric
What happens when the lower end of the lightning conductor is not properly buried in the ground?
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No earthing
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Building are protected
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Damage to building and even life
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Both a & c
Explanation
A lightning conductor taller than the building, 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 is buried deep in the ground to provide an easy route for the transfer of electric charge to the ground.
Earthing is important to protect building from lightning. If proper earthing is not provide than it can damage building and dangerous for life also.
Why should the height of lightning conductor is more than that of the walls of the building?
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Lightning get attracted towards the tallest target
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Lightning get repelled
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Lightning get attracted by the walls of building
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None of the above
Explanation
Tall structures on the ground, like buildings, provide a channel for the lightning to discharge into the ground. That's why lightning conductors should be taller than the building.
When you are in forest during lightning which is safe place?
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Open field
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Under tall trees
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Under short trees
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None of the above
Explanation
Lightning get attracted towards the tallest target, in forest it is good idea to take shelter under short trees to protect yourself from lightning.
To provide proper earthing, lower end of the lightning conductor should be
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buried deep into the ground
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slightly buried into the ground
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only touching the ground lightly
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a few inches above the ground
Explanation
To provide proper earthing, the lower end of the lightning conductor should be buried deep into the ground. Then the charges carried into the Earth will not be leaked on the surface of the Earth.
The uppermost layer of the Earth is:
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a huge single piece
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fragmented
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in two large pieces
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none of the above
Explanation
The Earth's crust is not a huge single piece. It is fragmented into pieces. Each fragment is called a tectonic plate and they are in
continuous motion, brushing past each other.
Fill in the blank:
The uppermost layer of the Earth is called _______.
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mantle
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outer core
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crust
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none of the above
Explanation
Earth consist of three parts core, mantle, crust. The uppermost layer is called crust.
Which of the natural phenomena are possible to occur due to earthquake?
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Tsunami
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Floods
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Landslides
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All of the above
Explanation
Disturbance deep inside the Earth's crust may lead to tsunami, floods, landslides etc.
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