Make your own charge detector. Take a paper strip roughly 10 cm x 3 cmGive it a shape as shown in Fig. 15.15. Balance it on a
needle. Bring a charged body near it. Observe what happens. Write
a brief report, explaining its working.
Answers
Answer:
Question 1.
What is lightning? What causes lightning?
Answer:
Lightning is also an electric spark, but on a huge scale. It is caused by the accumulation of charges in the clouds.
Question 2.
What is an electric charge? What are charged objects?
Answer:
When a plastic refill is rubbed with polythene it acquires a small electric charge. Similarly when a plastic comb is rubbed with dry hair, it acquires a small charge. These objects are called charged objects.
Question 3.
What is static charge? How does it differ from electric current?
Answer:
The electric charges generated by rubbing are called static charges. The static charges do not move while charges move in electric current.
Question 4.
What do you mean by electric discharge? How does it occurs?
Answer:
When the negative and positive charges meet, streaks of bright light and sound are produced. This process is called electrical discharge. For example, electric discharge occurring between two or more clouds or between clouds and earth.
Question 5.
What is earthing? What is the application of earthing?
Answer:
The process of transfer of charges from a charged object to the earth is called earthing. It is provided in buildings to protect from electrical shocks due to any leakage of electrical current.
Question 6.
How does electric discharge occur in clouds?
Answer:
At the time of thunder negative charges are accumulated near the clouds and positive charges near the ground. When these charges meet, electric discharge takes place between the ground and clouds. In this process, a large amount of energy is released.
Question 7.
What is lightning conductor? Where is it fixed?
Answer:
Lightning conductor is a device which is used to protect buildings from the danger of lightning. It is fixed at the top of the building.
Question 8.
What is an earthquake? How is it caused?
Answer:
Sudden shaking and trembling of earth is called an earthquake. It is caused mostly due to the movement of earth’s plates inside the crust.
Question 9.
What are fault zones? Name the fault zones in India.
Answer:
Since earthquakes are caused by the movement of plates, the boundaries of the plates are weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.
Question 10.
In India the most threatened areas or fault zones are Kashmir, Western and Central Himalayas, the Indo-Gangetic Plain, Rann of Kutch, etc.
Answer:
Tremors on the earth can also be caused when a volcano erupts, or a meteor hits the earth, or an underground nuclear explosion is carried out.
Question 11.
What are seismic waves? How are these waves recorded?
Answer:
The tremors produce waves on the surface of the earth. These are called seismic waves. These waves are recorded by an instrument called the seismograph.
Explanation:
the charged body w and detector will get attracted