NCERT Exemplar for Class 7 Science Solutions Chapter 14 Electric Current and Its Effects

Multiple Choice Questions 

1. When an electric current flows through a copper wire AB as shown in Figure 14.1, the wire 

Figure 14.1

(a) Deflects a magnetic needle placed near it. 

(b) Becomes red hot. 

(c) Gives electric shock. 

(d) Behaves like a fuse. 

Ans: The correct answer is option (a), Deflects a magnetic needle placed near it. A current carrying wire produces a magnetic field.

2. Choose the statement which is not correct in the case of an electric fuse. 

(a) Fuses are inserted in electric circuits of all buildings. 

(b) There is a maximum limit on the current which can safely flow through the electric circuits. 

(c) There is a minimum limit on the current which can safely flow in the electric circuits. 

(d) If a proper fuse is inserted in a circuit it will blow off if current exceeds the safe limit. 

Ans: The correct answer is option (c), There is a minimum limit on the current which can safely flow in the electric circuits. 

3. Three bulbs A, B, C are connected in a circuit as shown in Figure 14.2. When the
switch is ‘ON’ 

(a) Bulb C will glow first. 

(b) Bulb B and C will glow simultaneously and bulb A will glow after some time. 

(c) All the bulbs A, B and C will glow at the same time. 

(d) The bulbs will glow in the order A, B and C. 

Ans: The correct answer is option (c), All the bulbs A, B and C will glow at the same time. 

4. When a switch is in OFF position, 

(i) Circuit starting from the positive terminal of the cell stops at the switch. 

(ii) Circuit is open. 

(iii) No current flows through it. 

(iv) Current flows after some time. 

Choose the combination of correct answers from the following. 

(a) all are correct 

(b) (ii) and (iii) are correct 

(c) only (iv) is correct 

(d) only (i) and (ii) are correct 

Ans: The correct answer is option (b), Circuit is open and zero current flows through it. 

5. Which of the following precautions need not be taken while using electric

gadgets/appliances/circuits? 

(a) We should never touch a lighted electric bulb connected to the mains. 

(b) We should never experiment with the electric supply from the mains or a generator
or an inverter. 

(c) We should never use just any wire or strip of metal in place of a fuse. 

(d) We should never turn the switch in ON position. 

Ans: The correct answer is option (d), we should never turn the switch in ON position. 

Very Short Answer Questions

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

Ans: In order to make an electric fuse, the property of low melting point is used.

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

Ans: The device is known as a 'Miniature Circuit Breaker (MCB).

8. Fill in the blanks: 

(i) Our body is a ________________ of electricity. 

Ans: Conductor

(ii) An electric cell produces electricity from the __________ ___________ in it. 

Ans: Chemicals stored 

(iii) In an electric circuit a fuse is a _________ _______ to prevent possible fire. 

Ans: Safety Device

(iv) A combination of two or more cells is called a _________. 

Ans: Switch 

9. Unscramble the following words: 

i) TBTAYER 

Ans: BATTERY 

ii) SFEU

Ans: FUSE 

iii) HTRCO 

Ans: TORCH 

iv) HICWTS 

Ans: SWITCH 

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. 

Ans: No, Paheli's action was not correct. The heat produced by the electric bulb is a waste of electrical energy. She wasted a lot of energy by covering the bulb in her room with a towel at night to get a dull light.

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

Ans: The electric bulb consumes more electricity and wastes electricity in the form of heat. Compact fluorescent bulbs, on the other hand, do not squander electrical energy as heat and consume less energy.

12. Why is an electric fuse required in all electrical appliances? 

Ans: The word "electric fuse" refers to a safety device that prevents an electric circuit from overheating. It guards against harm to any electrical gadgets.

Short Answer Questions

13. Can we use the same fuse in a geyser and a television set? Explain. 

Ans: To heat water, a geyser is employed. As a result, geysers require a lot of electricity.

Pixels are displayed on a screen using television. As a result, compared to a geyser, television requires a lower rate of electricity.

As a result, separate fuses must be used in a geyser and a television set depending on the required rate of electricity.

14. Name two electric devices for each where 

(i) heating effect of current is used 

Ans: Current-heating devices are used: room heaters and geysers.

(ii) magnetic effect of current is used

Ans: Cranes and electric bells employ the magnetic influence of current.

15. Why do we cover plug pin holes which are within the reach of children with cello tape or a plastic cover when not in use? 

Ans: Any child that inserts his or her figure into the socket risks receiving an electric shock, which may be fatal. To protect children from receiving an electric shock, we cover plug pinholes with cello tape or a plastic cover.

16. Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give a reason. 

Ans: The magnetic effect is directly proportional to the number of wire turns on the electromagnet. As a result of the greater number of turns of wire on paheli's electromagnet, it will attract more pins. As a result, Paheli's electromagnet is the most powerful electromagnet.

Long Answer Questions

17. Your teacher has shown you the following activity. 

Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in Figure 14.3. The current is switched on and some pins are placed near the ends of the nail. 

Write down any three questions that come to your mind about this activity. 

Ans: a) The pins are drawn to the iron nail. Why?

b) What happens if the current is reduced or increased?

b) What happens if more than two cells are connected in an electric circuit?

18. Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in figure below. The current flowing in both the circuits is the same. 

i) Will the heat produced in both the cases be equal? Explain. 

Ans: The total sum of heat produced in each wire is proportional to its length (end to end distance). As a result, the total amount of heat produced in both circumstances will be different.

ii) Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain. 

Ans: No, the overall amount of heat produced by a wire is determined by its thickness or width. No, the quantity of heat produced in the wire is determined by its thickness.

19. How does the magnetic effect of electric current help in the working of an electric bell? Explain with the help of a diagram. 

Ans: The circuit of electric circuit is given below: 

Electric current travels through the coil when the circuit is turned on. The coil becomes magnetised due to the magnetic influence of electricity. This magnetised coil attracts a soft iron armature that is nearby. Because of this, the hammer makes a sound by striking the gong (bell). As a result, the bell begins to ring.

The magnetization of the coil and the flow of electricity will halt when the circuit is turned off. As a result, the bell stops ringing. 

20. Draw the symbols of the following circuit components. 

(i) Electric cell 

(ii) Switch in off position 

(iii) Electric bulb 

(iv) Battery 

Ans: The symbol of circuit components are:

Circuit Component	Symbol
Electric Cell
Switch in Off position
Electric bulb
Battery

About NCERT Solutions

Class 7 Science Solutions NCERT Exemplar Chapter 14 Electric Current and Its Effects include answers to all of the questions in the NCERT Exemplar book.  Vedantu contains solutions to a variety of problems of varying complexity that will assist you in learning more about Electric Current and Its Effects.

Fill it, match the column, problems on electronic circuit diagrams, true or false problems, their solutions, and full explanations for all multiple-choice questions are included in the NCERT Exemplar Class 7 Science Answers for the chapter Electric Current and Its Effects.

Solutions and explanations are provided for 5 multiple choice questions, 7 very short answer questions, 4 short answer questions, and 4 long answer questions in the NCERT Exemplar Class 7 Science Solutions Chapter 14 Electric Current and Its Effects.

NCERT Exemplar  Science Solutions for the chapter of  Electric Current and Its Effects, Standard 7, covers the following topics:

14.1 – Electric Component Symbols

14.2 – The Effect of Electric Current on Heating

14.3 – Electric Current Magnetic Effect

Electromagnet (14.4)

Electric Bell (14.5).

NCERT Exemplar  Science Solutions for the chapter of  Electric Current and Its Effects, Standard 7,  are quite important. Fundamentals of electric circuits, heating and magnetic effect of electric current, signs used in electric circuits, working of bulb filaments, fuse and MCB'S, uses of the magnetic effect of electric current, and operating of an electric bell are all covered in the NCERT Exemplar Class 7 Science Solutions Chapter 14 answer.