Test your knowledge of natural wonders with this quiz on Chapter 12, "Some Natural Phenomena," designed for 8th-grade science. Explore questions and answers covering topics like earthquakes, lightning, and storms. Perfect for students in the US looking to review key concepts or for anyone curious about the powerful forces of nature that shape our world. Get ready to learn and challenge yourself!
1) What are the two destructive natural phenomena discussed in this chapter?
Answer: The two destructive natural phenomena discussed in this chapter are lightning and earthquakes.
2) What steps can we take to minimize the destruction caused by natural phenomena?
Answer: We can take precautions and safety measures to minimize the destruction caused by natural phenomena.
3) Where can we commonly observe sparks in daily life?
Answer: Sparks can be observed on:
Electric poles when wires become loose.
Loose plugs in sockets.
4) What is lightning, and how is it similar to these sparks?
Answer: Lightning is an electric spark on a massive scale, similar to the sparks we see on electric poles or in sockets.
5) How did ancient people perceive lightning?
Answer: Ancient people did not understand the cause of lightning and believed it was the wrath of gods.
6) What causes lightning, according to modern understanding?
Answer: Lightning is caused by the accumulation of electric charges in the clouds.
7) How should we react to lightning?
Answer: We should not be afraid of lightning but must take precautions to protect ourselves from it.
8) What did the ancient Greeks know about electric charges?
Answer: As early as 600 B.C., the Greeks observed that when amber (a type of resin) was rubbed with fur, it attracted light objects like hair.
9) How can we observe similar phenomena today?
Answer: Similar phenomena can be observed when:
Taking off woolen or polyester clothes, causes hair to stand on end.
Removing clothes in the dark, where a spark and a crackling sound can be seen and heard.
10) What discovery did Benjamin Franklin make in 1752?
Answer: Benjamin Franklin showed that lightning and the spark from clothes are the same phenomena.
11) Why did it take so long to realize the similarity between lightning and sparks?
Answer: It took nearly 2000 years because scientific discoveries require extensive hard work and time.
12) What simple activity can help understand electric charges?
Answer: Rubbing certain materials, like amber, can help understand the nature of electric charges, a concept that can also be observed in games or everyday activities.
13) What happens when you rub a plastic scale on dry hair?
Answer: When a plastic scale is rubbed on dry hair, it acquires a small electric charge and can attract very small pieces of paper.
14) What do you observe when a plastic refill is rubbed with polythene?
Answer: The plastic refill acquires a small electric charge and can attract small pieces of paper.
15) What is meant by “charged objects”?
Answer: Objects like a plastic refill or a plastic comb, which acquire a small electric charge when rubbed (e.g., with polythene or dry hair), are called charged objects. In this process, the materials used for rubbing, such as polythene or hair, also get charged.
16) What is observed when two balloons is being rubbed with a woolen cloth?
Answer: The two balloons repel each other after being rubbed with a woolen cloth.
17) What happens when two charged objects made of the same material are brought close to each other?
Answer: They repel each other, as shown in the case of:
Two charged balloons.
Two charged refills.
18) What happens when two charged objects made of different materials are brought close to each other?
Answer: They attract each other, as shown when a charged balloon is brought near a charged refill.
19) What does the interaction between charged objects indicate?
Answer: Like charges repel each other.
Unlike charges attract each other.
20) How can we summarize the types of charges?
Answer: There are two kinds of charges:
Like charges (same type) repel each other.
Unlike charges (different types) attract each other.
21) What is the convention for the type of charge acquired by a glass rod rubbed with silk?
Answer: The charge acquired by a glass rod when rubbed with silk is conventionally called positive.
22) What is the nature of the charge on a plastic straw rubbed with polythene, if it is attracted to a charged glass rod?
Answer: Since the glass rod (positively charged) attracts the plastic straw, the straw must carry a negative charge. This is because opposite charges attract each other.
23) What happens when you touch a charged object with the end of a paper clip connected to two hanging aluminum foil strips?
Answer: The foil strips will repel each other.
24) Do the foil strips behave the same way when touched by different charged objects?
Answer: Yes, in general, the foil strips will repel each other when touched by any charged object.
25) Can an electroscope be used to detect whether a body is charged or not?
Answer: Yes, this simple setup can be used as an electroscope to detect the presence of a charge. If the foil strips diverge, it indicates that the object is charged.
26) Why do the foil strips repel each other in the electroscope?
Answer: The foil strips receive the same charge from the charged object through the paper clip (metals conduct electricity). Since like charges repel, the strips move away from each other.
27) What happens to the foil strips in the electroscope when you touch the paper clip with your hand?
Answer: The foil strips collapse and return to their original state.
28) Why do the foil strips collapse when touched by hand?
Answer: The foil strips lose their charge to the earth through your body.
29) What is the process of transferring charge from a charged object to the earth called?
Answer: The process is called earthing.
30) What is the purpose of earthing in buildings?
Answer: Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current.
31) How are charges separated during the development of a thunderstorm?
Answer: The upward movement of air currents and the downward movement of water droplets during a thunderstorm cause the separation of charges.
32) Where do the positive and negative charges accumulate in a thunderstorm cloud?
Answer: Positive charges tend to collect near the upper edges of the clouds, while negative charges accumulate near the lower edges.
33) What happens when the accumulated charges in a thunderstorm become very large?
Answer: The air, which is normally a poor conductor, can no longer resist the flow of charges. This leads to a discharge of electricity, resulting in lightning.
34) What is the process of lightning called?
Answer: The process of lightning is called an electric discharge.
35) Between which entities can the process of electric discharge occur?
Answer: Electric discharge can occur between two or more clouds, or between clouds and the earth.
36) What is the significance of hearing thunder during a thunderstorm?
Answer: Hearing thunder serves as an alert to seek immediate shelter in a safe place.
37) What should you do after hearing the last thunder?
Answer: After hearing the last thunder, it is advisable to wait for some time before coming out of the safe place.
38) Are open vehicles safe during a thunderstorm?
Answer: No, open vehicles like motorbikes, tractors, and open cars are not safe during a thunderstorm.
39) What precautions should be taken if you are caught in an open field during a thunderstorm?
Answer: If in an open field, stay far away from all trees, poles, or other metal objects.
40) Is it safe to carry an umbrella during a thunderstorm?
Answer: No, carrying an umbrella during a thunderstorm is not advisable.
51) What precautions should be taken inside the house during a thunderstorm?
Answer: Avoid contact with telephone cords, electrical wires, and metal pipes.
Avoid bathing.
Unplug electrical appliances like computers and TVs.
52) Is it safe to use electrical lights during a thunderstorm?
Answer: Yes, it is generally safe to use electrical lights during a thunderstorm.
53) What is a Lightning Conductor?
Answer: A Lightning Conductor is a device used to protect buildings from the effects of lightning.
54) How is a Lightning Conductor installed?
Answer: A metallic rod, taller than the building, is installed in the walls of the building during construction. One end of the rod is kept out in the air, and the other is buried deep in the ground.
55) How does a Lightning Conductor protect buildings?
Answer: The rod provides an easy route for the transfer of electric charge from the lightning strike to the ground, thus protecting the building.
56) Do metal columns, electrical wires, and water pipes in buildings offer any protection against lightning?
Answer: Yes, they offer some protection, but it is not advisable to touch them during a thunderstorm.
57) Which natural phenomenon is difficult to predict accurately?
Answer: Earthquakes are difficult to predict accurately.
58) What are the potential consequences of an earthquake?
Answer: Earthquakes can cause widespread damage to human life and property.
59) When did a major earthquake occur in North Kashmir?
Answer: A major earthquake occurred in Uri and Tangdhar towns of North Kashmir on 8 October 2005.
60) When did a major earthquake occur in Gujarat?
Answer: A major earthquake occurred in the Bhuj district of Gujarat on 26 January 2001.
61) What is an earthquake?
Answer: An earthquake is a sudden shaking or trembling of the earth that lasts for a very short time.
62) What causes earthquakes?
Answer: Earthquakes are caused by disturbances deep inside the earth's crust.
63) Is the earth's outermost layer a single piece?
Answer: No, the outermost layer of the earth is fragmented into pieces called plates.
64) What happens when these plates move?
Answer: When these plates brush past one another, it can cause tremors and earthquakes.
65) When did a major tsunami occur in the Indian Ocean?
Answer: A major tsunami occurred in the Indian Ocean on 26 December 2004.
66) What are the potential consequences of major earthquakes?
Answer: Major earthquakes can cause immense damage to buildings, bridges, dams, and people. They can also lead to loss of life and property, and trigger other disasters like floods, landslides, and tsunamis.
61) What happens when plates collide or move past each other?
Answer: These movements cause disturbances in the earth's crust, which manifest as earthquakes on the surface.
62) What are the weak zones where earthquakes are more likely to occur?
Answer: The boundaries of the plates, also known as seismic or fault zones, are the weak zones.
63) Can scientists accurately predict when and where the next earthquake will occur?
Answer: While scientists understand the causes of earthquakes, accurate prediction of the exact time and location of the next earthquake is not yet possible.
64) What are some other factors that can cause tremors on the earth?
Answer: Volcanic eruptions
Meteor impacts
Underground nuclear explosions
65) How is the power of an earthquake expressed?
Answer: The power of an earthquake is expressed in terms of magnitude on the Richter scale.
66) What is considered a destructive earthquake on the Richter scale?
Answer: Earthquakes with a magnitude higher than 7 on the Richter scale are considered destructive.
67) What are seismic waves?
Answer: Seismic waves are waves produced on the surface of the earth by tremors.
68) What instrument is used to record seismic waves?
Answer: Seismic waves are recorded by a seismograph.
69) How does a seismograph work?
Answer: A seismograph typically consists of a vibrating rod or pendulum that starts vibrating when tremors occur. A pen attached to the vibrating system records the seismic waves on a moving paper.
70) What information can scientists obtain from seismograph records?
Answer: Scientists can use seismograph records to construct a complete map of the earthquake and estimate its power to cause destruction.
71) Is the Richter scale a linear scale?
Answer: No, the Richter scale is not linear.
72) How does a 2-point increase in magnitude on the Richter scale affect the destructive energy of an earthquake?
Answer: An increase of 2 in magnitude on the Richter scale means 1000 times more destructive energy.
73) Can earthquakes be predicted accurately?
Answer: No, earthquakes cannot be predicted accurately at present.
74) What are some important precautions to take in areas prone to earthquakes?
Answer: Buildings in seismic zones should be designed to withstand major tremors.
People should be aware of emergency procedures and safe zones.
75) What are some important considerations for building structures in earthquake-prone areas?
Answer: Buildings should be designed to be "Quake Safe" with simple structures.
Consult qualified architects and structural engineers.
Consider using lighter materials like mud or timber in highly seismic areas.
Keep roofs as light as possible.
76) What precautions can be taken inside the house to minimize earthquake damage?
Answer: Secure cupboards and shelves to the walls.
Carefully consider the placement of wall clocks, photo frames, and water heaters to prevent them from falling.
Ensure all buildings, especially tall ones, have functioning fire-fighting equipment.
77) What steps should you take to protect yourself during an earthquake if you are at home?
Answer: Take shelter under a table and stay there until the shaking stops.
Stay away from tall and heavy objects.
If in bed, stay there and protect your head with a pillow.
78) What steps should you take to protect yourself during an earthquake if you are outdoors?
Answer: Find a clear spot away from buildings, trees, and overhead lines.
Drop to the ground.
79) What should you do if you are in a car or bus during an earthquake?
Answer: Remain in the vehicle.
Ask the driver to drive slowly to a clear spot.
Do not exit the vehicle until the tremors stop.
