NCERT Class VII Science Solutions: Chapter 14-Electric Current and its Effects Part 2

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VERY SHORT ANSWER QUESTIONS

Question 6:

Which property of a conducting wire is utilised in making electric fuse?

Answer:

Electric fuse wire is made from special material which has low meting point. When large electric current is passed through a circuit, it melts quickly and breaks the circuit and prevents damages to electric circuit.

Question 7:

Name the device used these days in place of electric fuses in electrical circuits.

Answer:

Miniature Circuit Breaker (MCB)

Image of Miniature Circuit Breaker

Miniature Circuit Breaker

Image of Miniature Circuit Breaker

Question 8:

Fill in the blanks:

  1. Our body is a __________ of electricity.

  2. An electric cell produces electricity from the __________ ________ in it.

  3. In an electric circuit a fuse is a _________ _______ to prevent possible fire.

  4. A combination of two or more cells is called a____________.

Answer:

  1. Our body is a conductor of electricity.

  2. An electric cell produces electricity from the chemicals stored in it.

  3. In an electric circuit a fuse is a safety device to prevent possible fire.

  4. A combination of two or more cells is called a battery.

Image of what is battery

What is Battery

Image of what is battery

Question 9:

Unscramble the following words:

  1. TBTAYER

  2. SFEU

  3. HTRCO

  4. HICWTS

Answer:

  1. Battery

  2. Fuse

  3. Torch

  4. Switch

Question 10:

Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel in the night to get dim light. Has she taken the right step? Give one reason to justify your answer.

Answer:

No. The towel may burn due to the heat produced by the bulb. Besides, it will also result in wastage of electric energy.

Question 11:

Why are compact fluorescent lamps (CFLs) preferred over electric bulbs?

Answer:

CFLs do not waste electricity as heat.

Image of what is compact fluorescent lamps

Compact Fluorescent Lamps

Image of what is compact fluorescent lamps

Question 12:

Why is an electric fuse required in all electrical appliances?

Answer:

To check the excessive flow of electric current