CBSE Class 8 Science Some Natural Phenomenon Assignment

Question. Which of the following cannot be changed easily by friction?
(a) A plastic scale
(b) A copper rod 
(c) An inflated balloon
(d) A woollen cloth
Answer: B

Question. When a glass rod is rubbed with a piece of silk cloth the rod
(a) and the cloth both acquire a positive charge.
(b) becomes positively charged while the cloth has a negative charge. 
(c) and the cloth both acquire a negative charge.
(d) becomes negatively charged while the cloth has a positive charge
Answer: B

True and False: 

Question. Like charges attract each other. 
Answer: False

Question. A charged glass rod attracts a charged plastic straw. 
Answer: True

Question. Lightning conductor cannot protect a building from lightning. 
Answer: False

Question. Earthquakes can be predicted in advance. 
Answer: False

Question. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
Answer: (i) Move to open space. Find a clean spot away from buildings, trees and overhead power lines. Drop to the ground.
(ii) If we are in a car or a bus, will not come out. Drive slowly to a clear spot and remain in it till the earthquake stops.

I. Fill in the blanks

1. The process of transferring of charge from a charged object to the earth is called ________.

2. The electrical charges produced by rubbing are ________ charges.

3. When charges move, they constitute an __________.

4. Earthing is provided in buildings to protect us from ___________.

5. The device which is used to test whether an object is carrying charge or not is called ____________.

6. The process of electric discharge between clouds and the earth or between different clouds causes ____________.

7. Like charges __________ each other.

8. Unlike charges ___________ each other.

II. Define

1. Lightning conductors

1.When two bodies are rubbed against each other,
(A) They acquire equal and opposite charges.
(B) They acquire similar charges.
(C) One body acquire a charge and the other remains uncharged.
(D) They acquire different amount of charges.

2.A body is said to have positive charge when,
(A) When it has excess of electrons.
(B) When it has lack of electrons.
(C) When it has equal protons and neutrons.
(D) None of these.

3.When the glass rod is rubbed with silk, which charge isproduced on each of the rods?
(A) Glass rod - positive charge; silk - negative charge.
(B) Glass rod - negative charge; silk - positive charge.
(C) Glass rod - neutral; silk - negative charge.
(D) Glass rod - positive charge; silk - neutral.

4.Which of the statements are true?
(A) Like charges attract each other.
(B) Like charges repel each other.
(C) Unlikecharges attract each other.
(D) Unlikecharges repel each other.

5.An electron is
(A) Positively charged
(B) Negatively charged
(C) Neutral
(D) None of the above.

6.The charges generated by rubbing are
(A) Static.
B) Moving.
C) Dynamic.
D) None of the above.

7.Which instrument is used to check whether the body is charged or not?
(A) Telescope.
(B) Lightning conductor.
(C) Microscope.
(D) Electroscope.

8.Charges flow from charged body to uncharged body.
(A) Until the entire charge flows from one part to the other.
(B) Until they both carry the same charge
.(C) Until they both become uncharged.
(D) Continuously

9.When an uncharged body touches a charged body, the
(A) Uncharged body acquires a similar charge
(B) Uncharged body acquires an equal and opposite charge.(C) Charge body loses it charge.
(D) Uncharged body remains uncharged.

10.During the earthquake one should
(A) Use the lift to get out of the building one is in
(B) Crawl under the table and cover one's head.
(C) Crouch near a window and protect one's head.
(D) Stand on the porch or balcony.

11.Which device is used to protect a building from the effect of lightning?
(A) Lightning electroscope.
(B) Electroscope.
(C) Lightning insulator.
(D) Lightning conductor.

12.Which type of rod is used in lightning conductor?
(A) Non-metallic
(B) Insulator
(C) Metallic
(D) Semiconductor

13. The intensity of earthquake is measured on the
(A) Modify Mercalli Scale
(B) Richter scale
(C) Seismic scale
(D) Mercury scale

14. The point on the surface directly above the seismic focus is called the
(A) Hypocentre
(B) Epicentre
(C) Seismic centre
(D) focus

15. Earthing is
(A) Transferring of charge from charged body to earth.
(B) Transferring of charge from earth to charged body.
(C) Transferring of charge from charged body to uncharged body.
(D) Transferring of charge from uncharged body to charged body.

16. Air is
(A) Good conductor of electricity.
(B) Bad conductor of electricity.
(C) Semiconductor of electricity.
(D) None of the above.

17.Which one is the good conductor of electricity?
(A) Air
(B) Glass
(C) Copper
(D) Plastic

18. Which one is theexample of bad conductor?
(A) Copper
(B) Silver
(C) Air
(D) Gold

19. Which place is safe during lightning?
(A) Inside house.
(B) Under tree.
(C) Open place.
(D) Open vehicles.

20. Name the place where the major earthquakehad occurred on 26th January 2001.
(A) Uri
(B) Bhuj
(C) Tangdhar
(D) Latur

21. The uppermost layer of the earth is called
(A) The mental
(B) The inner-core
(C) The outer core
(D) The crust

22. The fragments of the crust are called
(A) The plate
(B) The plane
(C) The zone
(D) The danger zone

23.Which natural phenomenon we cannot predict before?
(A) Thunder
(B) Flood
(C) Tsunami
(D) Earthquake

24.Which of the following cannot be charged easily by friction?
(A) A woolen cloth
(B) An inflated balloon
(C) A copper rod
(D) A plastic scale

25.A gold leaf electroscope can be used
(A) Only to detect a charge.
(B) Only to find the nature of charge.
(C) Only to measure the charge.
(D) To detect, measure and find the nature of the charge.

26.While testing for charge, …………. is used as a proofof charge.
(A) Attraction
(B) Repulsion
(C) Transfer of charge
(D) Earthing

27.The weak points on the earth's crust where earthquakes are likely to occur are called
(A) Plates.
(B) Weak zones.
(C) Danger zones.
(D) Tectonic plates.

28.Which of the following does not cause an earthquake?
(A) Volcanic activities.
(B) Nuclear explosion.
(C) Collapse of mines.
(D) Lightning.

29.What is the net charge on an atom?
(A) +1
(B) -1
(C) 0
(D) +2

30.What is the S.I. unit of charge?
(A) Coulomb
(B) Newton
(C) Pascal
(D) Ampere

31.The bottom part of lightning conductor is made up of:
(A) Aluminium
(B) Copper
(C) Nickel
(D) Silver

32.Sudden shaking of earth is called:
(A) Lightning.
(B) Earthing.
(C) Earthquake.
(D) Tsunami.

33.The ……….. produces waves on earth.
(A) Tsunami.
(B) Lightning.
(C) Earthquake.
(D) Tremors.

34.The waves produced by tremors called:
(A) Seismic waves.
(B) Tsunami waves.
(C) Tremor waves.
(D) Zone wave.

35.The instrument used to record seismic waves called:
(A) Electroscope.
(B) Seismograph.
(C) Seismoscope.
(D) None of these.

36.Interaction between two charged balloon is
(A) Attraction.
(B) Repulsion.
(C) Some times attraction and some times repulsion.
(D) None.

37.The interaction between a charged balloon and a charged refill is:
(A) Attraction.
(B) Repulsion.
(C) Some times attraction and some times repulsion.
(D) None.

38.The electric discharge can occur between ………. and ………..
(A) Cloud and Cloud.
(B) Cloud and Earth.
(C) (a) & (b).
(D) None.

39.Hearing……… is the alert to rush to a safe place.
(A) Lightning.
(B) Thunder.
(C) (a) & (b).
(D) None.

40.Mention two causes of earthquake other than movements of tectonic plates?

41.What are the weak points, where earthquakes are likely to occur, on the earth crust called?

42.What is Tsunami?

43.Which scale is used to measure intensity of earthquake?

44.What is an electroscope?

45.What is lightning?

46.List two states in India where earthquakes are more likely to strike.

47.What happens when an ebonite rod is rubbed with fur?

48.What happens when ebonite rod is brought near a freely suspended and charged ebonite rod?

49.What is mean by electrification by friction?

50.Write the name of methods by which we can charge an uncharged body.

51.Mention two hazards caused by earthquake.

52.What is seismograph?

53.What do you mean by electric current?

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54.What are tectonic plates?

55.What is lightning conductor?

56.What is earthing?

57.What is electric discharge? Give two examples of electric discharge.

58.What is thunderstorm? How is it produced?

59.What is earthquake?

60.Draw a neat diagram of map of the earth quake.

61.State the properties of changes.

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62.What causes the earthquakes? Which scale is used to measure intensity of earthquake?

63.Suggest three measures to protect ourselves from lightning.

64.Draw the diagram of an instrument, which can be used to detect a charged body.

65.Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?

66.Suppose you are at your home and an earthquake strikes. What precaution would you take to protect yourself?

67.What is earthing? Why earthing provided in buildings?

68.Sometimes, a crackling sound is heart while taking off a sweater during witness. Explain

69.Draw a neat labeled diagram structure of the earth.

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70.Explain briefly the process of lightning.

71.Write causes of earthquake and explain briefly two hazards caused by earthquake.

72.State the charge produced by friction in each of following pairs:
(i) Fur and glass (ii) Flannel and ebonite (iii) Glass and silk (iv) Fur and rubber (v) Shellac and silk

73.Describe briefly the construction of a seismograph with a neat labelleed diagram.

74.What are the precautions to be taken to make the building "quake safe"?

75.Describe an activity to show that like charge repel each other and unlike change attract

Q1. What type of electric charge is acquired by a rubber balloon when rubbed with awoolen cloth?

Q2. A positively charged object repels another charged object kept close to it. What is the nature of charge on the other object?

Q3. A glass rod is rubbed with a silk cloth & a rubber balloon is rubbed with a woolen cloth.

a) Which two objects acquire negative charge?

b) Which two objects acquire positive charge?

Q4. Explain why, a glass rod can be charged by rubbing when held by hand but an iron rod cannot be charged by rubbing, if held by hand?

Q5. Consider three charged bodies P, Q & R. If P & Q repel each other & P attracts R. What is the nature of force between Q & R?

Q6. Name the device used to detect electric charge on a body. Draw its labeled diagram.

Q7. What will you observe when the metal cap of an electroscope is touched with a glass rod which has been rubbed with silk cloth? Give reason for your answer.

Q8. What are the uses of an electroscope? (3 points)

Q9. Why do the leaves of a gold leaf electroscope diverge when a charged body is brought in contact with its disc?

Q10. Do the leaves of an electroscope always diverge to the same extent when a charged body is brought in contact with its disc?

Q11. What will you observe when the metal cap of an electroscope is touched with:

a) A positively charged object?

b) A negatively charged object?

Q12. What happens to the charge on an electroscope when its disc is connected to that of an uncharged electroscope with the help of a conducting wire? What happens to the leaves of the two electroscopes?

Q13. What would you expect in the following cases?

a) A glass rod rubbed with a piece of silk is brought near a negatively charged paper cylinder.

b) A negatively charged body is brought in contact with the disc of a positively charged electroscope.

c) Someone touches the disc of a negatively charged electroscope.

Q14. What will be the charge

a) on the metal cap &

b) on the leaves of an electroscope, if you bring a positive rod near the end of its metal cap.

Q15. What will be the charge

a) on the metal cap &

b) on the leaves of an electroscope, if you bring a positive rod in contact with its metal cap.

Q16. Explain why a charged body loses its charge when we touch it with our hand.