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How lightning occurs? - class-VIII

Description: how lightning occurs?
Number of Questions: 27
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Tags: analysis of natural phenomena physics some natural phenomena static electricity
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How does lightning occurs between two charges within the cloud?

  1. When two negative charges grow large enough then a giant lightning sparks occurs

  2. When positive and negative charges grow large enough then a giant lightning sparks occurs

  3. When two positive charges grow large enough then a giant lightning sparks occurs

  4. None


Correct Option: B
Explanation:

Build up of electrostatic charge in the clouds results in lightning. During this event, one region of the cloud is accumulated with positive charge whereas the other region is accumulated with negative charge.Hence when positive and negative charges grow large enough ,the air present being non-conductive no more resists the flow of charges and electric discharge can be seen in the form of giant lightning sparks.

What is the approximate lightning frequency?

  1. 1.4 billion flashes per year

  2. 1.4 billion flashes per month

  3. 1.5 billion flashes per year

  4. 1.6 billion flashes per year


Correct Option: A
Explanation:

It is estimated that lightning strikes 40-50 times every second, i.e., almost 1.4 billion flashes per year.

What is meant by lightning?

  1. It is sudden electrostatic discharge during an electrical storm between electrically charged regions of cloud.

  2. It is sudden electrostatic discharge during an electrical storm between non-electrically charged regions of cloud.

  3. It is unsudden electrostatic discharge during an electrical storm between electrically charged regions of cloud.

  4. None of the above


Correct Option: A
Explanation:

Lightning occurs when there is a build up of the electrostatic charge in clouds. Regions within the cloud, one builds up a positive whereas other builds up a negative charge.

Lightning is formed in unstable atmospheric zones where there is typically a lot of ____ and ______.

  1. Heat, moisture

  2. Heat, vapour

  3. Heat, gas

  4. Heat, lava


Correct Option: A
Explanation:

Lightening is an extremely high voltage, high current, transient electrical discharge. It is most commonly caused by charge separation in cumulonimbus clouds, or "thunderheads". These type of clouds typically are very dynamic with strong ascending and descending air currents. They are formed in unstable atmospheric zones where there is typically lot of heat and moisture.

The layer of the earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio wave is known as

  1. Ionosphere

  2. Stratosphere

  3. Mesosphere

  4. Exosphere


Correct Option: A
Explanation:

The layer of the earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio wave is known as the ionosphere.

Fill in the blank.
Static electricity produced by charged particles in the atmosphere is known as_______.

  1. Atmospheric electricity

  2. Atmospheric charge

  3. Cloud electricity

  4. Wind electricity


Correct Option: A
Explanation:

Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of electric discharge. The static electricity produced by charged particles in the atmosphere is known as atmospheric electricity.

Fill in the blank
________ is pattern of electrical charges in Earth's atmosphere.

  1. Electricity

  2. Space electricity

  3. Ground electricity

  4. Atmospheric electricity


Correct Option: D
Explanation:

Atmospheric electricity is the pattern of electrical  charges in Earth's atmosphere. Atmospheric electricity refers to electricity that exists in the atmosphere as a result of natural phenomenon. 

The Earth's surface, the ionosphere and the atmosphere is known as :

  1. global atmosphere electrical circuit

  2. local atmosphere electrical circuit

  3. electrical circuit

  4. none of these


Correct Option: A
Explanation:

The normal movement of electric charges among the Earth's surface, the various layers of atmosphere and especially the ionosphere, taken together are known as Global atmosphere electric circuit.

Ionosphere extends from about 80 to 1,000 km :

  1. above the earth's surface

  2. above the sea's surface

  3. below the sea's surface

  4. none of the above


Correct Option: A
Explanation:

The ionosphere is the ionised part of earth's upper atmosphere. It is the layer that extends from about $80$ to $1000$ Km above the earth's surface.

Fill in the blank.
_______is most commonly caused by charge separation in cumulonimbus clouds, or thunderheads.

  1. Strom

  2. Lightning

  3. Cyclone

  4. Hurrican


Correct Option: B
Explanation:

Lightening is an extremely high voltage, high current, transient electrical discharge. It is most commonly caused by charge separation in cumulonimbus clouds or thunderheads. 

The normal movement of electric charges among the Earth's surface, the various layers of the atmosphere, and especially the ionosphere, taken together, are known as :

  1. the global atmospheric electrical circuit

  2. a current conducting circuit

  3. charge cloud

  4. none of the above


Correct Option: A
Explanation:

Atmospheric electricity is the pattern of electrical charges in the earth's atmosphere. The normal movement of electric charges among the earth's surface, the various layers of the atmosphere, and especially the ionosphere, taken together, are known as the global atmospheric electrical circuit.
Much of the reasoning required to explain these currents lies within the field of electrostatics, but also requires understanding of other disciplines within Earth science.

The intensity of the atmospheric electric field is, normally,

  1. greater in the middle of the day than at morning

  2. smaller in the middle of the day than at morning

  3. same in the middle of the day as at morning

  4. zero in the middle of the day and at morning


Correct Option: A
Explanation:

The fine day net positive charge sets up an electric field between the negative earth and the net positive charge in the air and this electric field stores electrical energy. The positive charge acts by induction on the earth and electromagnetic devices.

The explanation for atmospheric electricity mainly lies in the field of

  1. electromagnetism

  2. electrostatics

  3. current electricity

  4. All of the above


Correct Option: B
Explanation:
The phenomenon of atmospheric electricity is observed mainly explained by the presence of static charges in various object. The neutralisation effect of these charges can be seen as atmospheric electricity. And the study of static charges is known as electrostatics

Which of the following is an example of atmospheric electricity?

  1. Auroras

  2. Lightening

  3. Ionospheric currents

  4. All of the above


Correct Option: D
Explanation:
Examples of atmospheric electricity
(a) Auroras $\rightarrow$ appearance of streamer of reddish light in the sky, especially near northern or southern magnetic pole.
(b) Lightning
(c) Ionospheric currents

When there is lightning and 
a) You are in a jungle ,go under a tall tree.
b) You are in a jungle,go under a canopy of small trees and bushes.
c) You are out in the open,crouch on your feet,do not stand up or lie on the ground.
d) You are in an open field,stay there rather than go inside a completely covered building.Of these the good strategies are :-  

  1. B and C

  2. A and C

  3. A,B and C

  4. A,C and D


Correct Option: A
Explanation:

When there is lightning and you are in a jungle, its better to go under a canopy of small trees and bushes. The electric field is strongest near the pointed tip of an electrical conductor, and so isolated trees often make for great targets for lightning strikes. Canopy of small trees delocalises charge concentration on the other hand. 

Standing out in a field far from trees may also pose risks too as it makes you  the tallest object around and may be a target for lightning strikes. The idea will be to crouch low so that you are not the tallest object around, and at the same time keep your feet close together with your heels touching. This will help the electricity to go in one foot and out the other.

The intensity of atmospheric electric field is :

  1. same in winter as in summer

  2. lesser in winter than in summer

  3. greater in winter than in summer

  4. none of the above


Correct Option: C
Explanation:
Experiments have shown that the intensity of the electric field is greater in the middle of the day than at morning or night and is also greater in winter than in summer, which is totaly based on 'Fine weather' theory.

There are $4\times 10^{23}$ atoms in a metal sphere. If one electron is removed from 0.1% atom. what will be the charge on the sphere?

  1. $64C$

  2. $6.4C$

  3. $0.64C$

  4. $-6.4C$


Correct Option: A

Clouds get electrically charged when :

  1. The UV rays of sun falls on them

  2. Air molecules rub against water molecules

  3. Cold currents of air rub against hot currents of air

  4. Both B and C


Correct Option: D
Explanation:

The heat from the sun and warm air cause water from water bodies to vaporize. These vapour accumulate in the sky to form clouds. When these vapour molecules rub against the air molecules or other vapour molecules, they acquire charge due to friction.

Lightning occurs when an electrical charge is built up within a cloud, due to static electricity generated by supercooled water droplets colliding with ice crystals near the freezing level. When a large enough charge is built up, a large discharge will occur and can be seen as lightning. The temperature of a lightning bolt can be five times hotter than the surface of the sun. 

Both B and C are correct.
Option D 

A lightning rocket is a device used to control 

  1. time and location of a lighting strike.

  2. fuel and location of a lighting strike.

  3. the lighting of the strom

  4. none of the above


Correct Option: A
Explanation:

A lightening rocket is a rocket device, about the size of a man, that trails behind a conductor, such as fine copper wire. It is therefore, a conducting lightening rod which is grounded and positioned along side the launch tube in communication with the conductive path to thereby control time and location of a lightening strike from the thundercloud.

Which of the following statement is correct?

  1. The earth's surface is negatively charged

  2. The earth's surface is positively charged

  3. The earth's surface is neutral

  4. None of the above


Correct Option: A
Explanation:

The earth's surface is negatively charged.


Answer-(A)

Electric discharges in the atmosphere is associated with natural phenomena such as :

  1. lightning

  2. reflecting

  3. refracting

  4. none of the above


Correct Option: A
Explanation:

$Lightning$ is the natural phenomena of electric discharge through atmosphere.


Answer-(A)

Atmospheric electricity is generated due to 

  1. the accumulation of static charges

  2. the accumulation of moving charges

  3. the destruction of static charges

  4. destruction of moving charges


Correct Option: A
Explanation:

The presence of electrical action is the atmosphere, due to the accumulation of enormous static charges generated by friction of air upon itself, can be accounted for the generation of atmospheric electricity i.e, lightening and thunderstorms. 

The theory of atmospheric electricity explains which of the following phenomena?

  1. Free electricity causes thunderstorms

  2. Current due to a charge

  3. The high temperature causes people

  4. None of the above


Correct Option: A
Explanation:
Atmospheric electricity is the study of electrical charges in the Earth's atmosphere (or that of any planet). One of the phenomenons that is a result of this is that free electricity causing thunderstorm.

Static charges in the atmosphere is generated by

  1. induction from the earth's surface

  2. conduction between clouds

  3. friction of the air upon itself

  4. No reason


Correct Option: C
Explanation:

The accumulation of enormous static charges in the atmosphere is generated by the friction of air upon itself. Such accumulation of static charges in the atmosphere can be the cause of atmosphere electricity. 
.

Atmospheric electricity was discovered by

  1. Isaac Newton

  2. Michael Faraday

  3. Benjamin Franklin

  4. Thomas Edison


Correct Option: C
Explanation:

Atmospheric electricity is the study of electrical charges in the earth's atmosphere. Benjamin Franklin discovered it. His experiments showed that electrical phenomenon of atmosphere were not fundamentally different from those produced in the laboratory by listing many similarities between electricity and lighting. 

State whether the given statement is True or False :

Lightning conductor always develops the opposite charges as is the charge in the clouds.

  1. True

  2. False


Correct Option: A
Explanation:

Lightening conductor always develops the opposite charges as in the charge in the clouds. This statement is true. Because according to the lightening dissipative theory, which states that as a cloud approaches a building, there is a conductive pathway established between the statically charged cloud and lightening rod. The charge induced by the cloud on lightening rod is opposite to that  on the cloud. According to this theory, static charges gradually migrate along this pathway to the ground, thus reducing the explosive discharge.

The lower portion of a charged cloud generally carries .............. .

  1. Apositive charge

  2. Anegative charge

  3. Air

  4. No charge


Correct Option: A
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