Some Natural Phenomena - Worksheets

CBSE Worksheet-01
Class–VIII Science (Some Natural Phenomena)

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1. When a comb is rubbed against hair, force generated in it is :-
   1. muscular force
   2. gravitational force
   3. frictional force
   4. electrostatic force
2. Clouds can charge tall buildings and trees by :-
   1. friction
   2. induction
   3. conduction
   4. gravitation
3. The waves generated by an earthquake are called :-
   1. tectonic waves
   2. internal waves
   3. seismic waves
   4. tsunami
4. Charges are of two kinds:-
   1. negative and positive
   2. negative and neutral
   3. positive and neutral
   4. neutral and static
5. Match the column :-

   a. glass rod rubbed with silk	i) attract each other
   b. like charges	ii) positive charge
   c. ebonite rod rubbed with wool	iii) transferring of charge
   d. Earthing	iv) repel each other
   e. unlike charges	v) negative charge

6. Fill in the blanks :-
   1. The electrical charges generated by rubbing are ______ .
   2. Tall buildings are protected from damage by lightning through a lightning ______ .
   3. The simplest form of a seismograph is a simple ______ .
   4. Magnitude and intensity of earthquake is measured by ______ scale.
   5. Lithosphere of earth is divided into about 20 parts called ______ plates.
7. Describe how tsunamis form?
8. What causes an earthquake?
9. Name the type of electricity that will be produced?
   

CBSE Worksheet-01
Class–VIII Science (Some Natural Phenomena)
[Answer]

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1. d
2. b
3. c
4. a
5. a. ii, b. iv, c. v, d. iii, e. i.
6. 1. static
   2. conductor
   3. pendulum
   4. Richter
   5. tectonic
7. A disturbance such as an earthquake, landslide, volcanic eruption, or meteorite impact can generate a series of waves in an ocean or other body of water. Undersea earthquakes occur around tectonic plates and faults cause the water above to be moved up or down.When movement along a fault moves the seafloor upward, water is also pushed upward and becomes tsunami waves. As the waves approach shallower water, they become higher.
   
8. An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time. It is caused by a disturbance deep inside the earth’s crust. It is the vibration, sometimes violent, of the Earth's surface that follows a release of energy in the Earth's crust. This energy can be generated by:
   1. a sudden dislocation of segments of the crust i.e. faults.
   2. volcanic eruptions
   3. man-made explosions
   4. movement of tectonic plates
      The most common kind of quakes, the most destructive and the kind people generally have in mind when we think of earthquakes are the ones that are caused by the sudden dislocation of large rock masses along the faults within the earth's crust. A fault is a fracture within some particular rocky mass within the earth's crust. Fault sizes can vary greatly, as some faults can be miles long. Earthquakes are caused by active faults, which are, faults along which the two sides of the fracture move with respect to each other.In short, an earthquake is caused by the sudden movement of the two sides of a fault with respect to another.
9. It is the static electricity that will be produced.