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CBSE Questions for Class 8 Physics Some Natural Phenomena Quiz 6 - MCQExams.com
CBSE
Class 8 Physics
Some Natural Phenomena
Quiz 6
Earthquake is also known as :
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nektons
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blusters
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temblors
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flickers
Explanation
An
earthquake
also known
as
a temblor, quake
, tremor is the shaking of the surface of the Earth resulting from
a
sudden release of energy in the Earth's crust that creates
seismic
waves.
Lightning conductor is made up of conducting materials.
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True
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False
Explanation
The lightning conductor is made of conducting material such as copper as it allows the electric charges to pass through it. So, the given statement is true.
Which of the following is/are true regarding Earthquake ?
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It refers to shaking of the Earth.
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It occurs due to release of energy.
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It generates waves that travel in all direction.
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All of the above.
Explanation
Earth's crust is broken up into large pieces called tectonic plates. Tectonic plates are giant pieces of the Earth's crust that fit together and move around on the Earth's surface.
Tectonic plates are constantly moving slowly, but sometimes friction between them causes them to lock together and become unable to move. The rest of the plates carry on moving, which leads to increased pressure on the locked section. Eventually, the locked section succumbs to the pressure, and the plates move past each other rapidly. This movement causes a tectonic earthquake. The waves of released energy move through the Earth's crust in all direction and cause the shaking we feel at an earthquake site.
Object may acquire an excess or deficiency of charge by
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Electric force
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Heating
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Shaking
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By rubbing
Explanation
An object can be charged by rubbing. During rubbing some of the free electrons may get transferred from one object to another.
Earthquake waves are of which type?
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Infrasonic
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Ultrasonic
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Supersonic
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Intrasonic
Explanation
Infrasonic
Earthquake waves have frequencies less than $$20 \ Hz$$, thus they are infrasonic waves.
Seismic waves that vibrate perpendicular to the direction of their path.
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Spread on the surface of the earth
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Travel through the solid as well as other parts of the earth
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Travel through the solid parts of the earth only
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None of the above
Explanation
Seismic waves that vibrate perpendicular to the direction of motion travel through the solid parts of earth only.
State whether the given statement is True or False :
The plates of the outermost layer of the Earth are always in continuous motion.
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True
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False
Explanation
The outermost layer of the Earth is called as crust. It is not in one piece but fragmented. Each fragment is called as a plate. Such 7-8 major plates are present. Also, there are many minor plates. These plates are in continuous motion. When these plates brush past one another or a plate goes under another, it causes collision. This causes earthquake on the surface of the Earth. Earthquakes occur all the time around the world. But they are too small to be noticed. Major earthquakes are less frequent. Hence, given statement is true.
Consider the list of terms given below:
(i) Seismic Zone
(ii) Fault Zone
(iii) Mantle
(iv) Inner Core
The boundaries of the Earth's plates are known as:
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(i) and (ii)
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(i) and (iii)
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(iii) and (iv)
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(ii), (iii) and (iv)
Explanation
Seismic zone is the earthquake prone area, where the boundaries of Earth plates are situated. Seismic zones are located along the fault zones.
Within the Earth's crust, f
ault zone
is the boundaries between the plates, such as subduction zones or transform faults.
The mantle is a layer between the crust and the outer core.
The inner core is the very center of the Earth.
Major earthquakes are less likely to occur in
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North East India
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Rajasthan
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Rann of Kutch
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Orissa
Explanation
North East India, Rajashthan and Rann of Kutch are within moderate to high intensity earthquake zones of India. Orissa, on the other hand, belongs to low intensity earthquake zone of India.
Seismic waves is recorded by an instrument called seismograph.
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True
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False
Explanation
The tremors produce waves on the surface of the earth. These are called seismic waves. The waves are recorded by an instrument called the seismograph.
Devices which are used to detect the presence of static electricity over a body is
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Magnetoscope
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Stethescope
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Sphygomenometer
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Electroscope
Lightning conductors are used to save the building from earthquakes.
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True
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False
Explanation
Lightning conductors are metallic conductors which act as a path for the flow of current that is discharged through a lightning strike.
Hence, lightning conductors save buildings from lightning strikes not earthquakes.
Given statement is $$False$$.
State whether given statement is True/False ?
Lightning conductor is made up of copper.
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True
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False
Explanation
Lighting conductor should be made-up of thick copper conductor because it posses low resistance. When the lighting strikes on the rod, Rod allows this heavy current to discharge into the ground without producing lots of heat.
A polyethylene strip rubbed against a woollen cloth can attract small pieces of paper. Which of the following changes takes place on small pieces of paper during the application of the force ?
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The shape of the object.
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The position of the object.
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The density of the object.
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The mass of the object.
A lightning conductor installed in a building :
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Does not allow the lightning to fall on the building
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Repels the lightning
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Forces the lightning to fall in an area where there are no buildings
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Conducts electric charge to the ground when lightning strikes the building
Explanation
Lightning conductors are installed in buildings to provide a path for electric discharge during lightning strike and let them to reach the ground and protect the building from lightning strike.
Answer-(D)
Which of the following is the best thing to do during heavy lightning?
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Lying on the ground in an open place
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Going into the nearest water body
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Staying indoors, away from metallic doors or windows
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Standing under a tall tree
Explanation
Staying indoors away from metallic doors or windows is the best thing to do during heavy lightning.
If an ebonite rod rubbed with fur and a glass rod rubbed with silk cloth are brought nearer to each other, then what happens?
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They will attract each other.
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They will repel each other.
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Nothing will happen to them.
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They will get heated up.
Explanation
On rubbing the ebonite rod with fur, electrons move from fur to the ebonite rod. Hence, the ebonite rod becomes negatively charged.
When the glass rod is rubbed with silk cloth, glass quickly loses electrons and silk takes electrons. Hence, the glass rod becomes positively charged.
Since, unlike charges attract each other. Hence, if an ebonite rod rubbed with fur and a glass rod rubbed with silk cloth are brought closer to each other, they will attract each other.
The weak zone around the boundaries of plates underneath the Earth, which is prone to slide and cause an earthquake is commonly known as :
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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
The weak zone around the boundaries of plates underneath the earth, which is prone to slide and cause an earthquake is known as Seismic or Fault Zones.
The correct option is A.
The streaks of bright light seen during lightning is essentially the path followed by:
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UV rays from sun
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Gamma rays
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Accumulated electric charges
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None of the above
Explanation
Lightning occurs due to electrostatic discharge between the atmosphere and the ground. So t
he streaks of bright light seen during lightning are essentially the path followed by accumulated electric charges.
Which of the following is the best thing to do during heavy lightning ?
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Lying on the ground in an open place
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Going into the nearest water body
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Staying indoors away from metallic doors or windows
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Standing under a tall tree
Explanation
A house or a building is a safe place to stay protected from lightning strikes. However, lightning can strike telephone cords, electrical wires, and metal pipes. Therefore, during a thunderstorm, we should avoid any contact with metal bodies.
Magnitude of earthquake is measured by :
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Electroscope
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Richter scale
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Seismograph
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Screw Guage
Explanation
A seismograph is an instrument used to detect and record earthquakes, whereas - a Richter scale is a quantitative measure of the power or magnitude of an earthquake. It is also known as the Richter Magnitude Scale.
So the correct option is B.
Earthquakes at two places $$A$$ and $$B$$ were measured by a seismograph which recorded the magnitude as $$2$$ and $$4$$. The magnitude of tremors and their destructive energy at $$A$$ and $$B$$ can be compared as:
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Tremors at $$B$$ are two times that at place $$A$$
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Tremors at $$B$$ are four times that at place $$A$$
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Tremors at $$B$$ are $$100$$ times that at place $$A$$
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Tremors at $$B$$ are $$1000$$ times that at place $$A$$
Explanation
Richter scale is not linear. An earthquake of magnitude $$4$$ is not twice destructive as an earthquake of magnitude $$2$$. An increase of $$2$$ in magnitude means $$1000$$ times more destructive energy. Therefore, Tremors at $$B$$ are $$1000$$ more destructive energy than
that at place
$$A$$.
Which of the following country in the world is most prone to earthquake?
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India
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America
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China
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Japan
Explanation
Since, Japan is located in an area where several tectonic plates meet. Hence, it is most prone earthquake.
Which of the following event can cause earthquake?
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Volcanic eruption
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Meteor hitting earth
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Underground nuclear explosion
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All of the above
Explanation
An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time. Most earthquakes are caused by the movement of earth’s plates. Tremors on the earth can also be caused when a volcano erupts, or a meteor hits the earth, or an underground nuclear explosion occurs.
A .......... protects a building from lightning.
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Seismograph
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Electroscope
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Lightning conductor
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None of these
An
ebonite rod is rubbed with fur. Which of the following statements are true?
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Electrons move from fur to the ebonite rod.
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Electrons move from ebonite rod to the fur.
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There will be no transfer of electrons
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After rubbing both will have the same type of charge
Explanation
Ebonite rod gains electrons from the fur when it is rubbed with fur. Thus ebonite has more negative charges as compared to positive charges in the nucleus. Thus, on the whole, the ebonite rod gets negatively charged.
Earthquake at two places A and B were measured by a seismograph which recorded the magnitude as 4 andThe magnitude of tremors and its destructive energy at A and B can be compared as under:
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Tremor at B is 2 times to that at place A
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Tremor at B is 4 times to that at place A
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Tremor at B is 100 times to that at place A
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Tremor at B is 1000 times to that at place A
Explanation
Richter scale is not a linear scale. It is a logarithmic scale. A difference in magnitude of $$2$$ implies a multiplication factor of $$10^2 = 100$$.
Lightning conductor installed in a building:
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does not allow the lightning to fall on the building
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repels the lightning
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forces the lightning to fall in an area where there are no buildings
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conducts electric charge to the ground when lightning strikes the building
Explanation
Lightning conductor is installed in a building so that when a lightning strikes the building it goes to the conductor and the conductor will conduct this electric charge due to lightning to the ground and the building will be safe.
An ebonite rod is rubbed with fur. What will be the charge on the ebonite rod?
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Negative
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Positive
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Neutral
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Can't say
Explanation
On rubbing the ebonite rod with fur, electrons move from fur to the ebonite rod. The electrons in fur are less tightly bound than electrons in ebonite and hence ebonite gets a negative charge. The charge on the ebonite rod is negative and the charge on the fur is positive.
An ebonite rod is rubbed with fur. What is the charge on the fur?
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Positive
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Negative
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Neutral
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None of these
Explanation
Explain the charging of the ebonite rod and the fur on the basis of electron movement. Solution: When an ebonite rod is rubbed with fur, fur loses electrons and the ebonite rod gains electrons. fur becomes positively charged and rod becomes negatively charged.
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