by Tiwari Academy
NCERT Solutions for Class 8 Science Curiosity Chapter 4 Electricity: Magnetic and Heating Effects for Session 2025-26. It explains the fascinating behavior of electric current and its dual effects. The chapter highlights how current produces heat, used in appliances like electric heaters, bulbs and magnetic effects, which operate devices like electric appliances. With solved exercises, clear explanations and practical examples, these solutions help students strengthen their understanding, enhance problem-solving skills and prepare effectively for exams.
Class 8 Science Curiosity Chapter 4 MCQ
Class 8 Science Old Book Chapter 4 MCQ
Class 8 Science Old Book Chapter 4 Solutions
Electricity: Magnetic and Heating Effects Class 8 Science Curiosity Chapter 4 Keep the curiosity alive
1. Fill in the blanks:
(i) The solution used in a Voltaic cell is called ________.
(ii) A current carrying coil behaves like a ________.
See Answer(i) The solution used in a Voltaic cell is called electrolyte.
(ii) A current carrying coil behaves like a magnet.
2. Choose the correct option:
(i) Dry cells are less portable compared to Voltaic cells.
See AnswerFalse (Dry cells are more portable, Voltaic cells are bulky).
(ii) A coil becomes an electromagnet only when electric current flows through it.
See AnswerTrue
(iii) An electromagnet, using a single cell, attracts more iron paper clips than the same electromagnet with a battery of 2 cells.
See AnswerFalse (More cells mean stronger current and stronger magnet).
Class 8 Science Curiosity Chapter 4 Question 3 and 4
3. An electric current flows through a nichrome wire for a short time.
(i) The wire becomes warm.
(ii) A magnetic compass placed below the wire is deflected.
Choose the correct option:
(a) Only (i) is correct
(b) Only (ii) is correct
(c) Both (i) and (ii) are correct
(d) Both (i) and (ii) are not correct
See Answer(c) Both (i) and (ii) are correct
4. Match the items in Column A with those in Column B:
| Column A | Column B |
|---|---|
| (i) Voltaic cell | (a) Best suited for electric heater |
| (ii) Electric iron | (b) Works on magnetic effect of electric current |
| (iii) Nichrome wire | (c) Works on heating effect of electric current |
| (iv) Electromagnet | (d) Generates electricity by chemical reactions |
Answer:
| Column A | Column B |
|---|---|
| (i) Voltaic cell | (d) Generates electricity by chemical reactions |
| (ii) Electric iron | (c) Works on heating effect of electric current |
| (iii) Nichrome wire | (a) Best suited for electric heater |
| (iv) Electromagnet | (b) Works on magnetic effect of electric current |
Class 8 Science Curiosity Chapter 4 Question 5, 6 and 7
5. Nichrome wire is commonly used in electrical heating devices because it
(i) is a good conductor of electricity.
(ii) generates more heat for a given current.
(iii) is cheaper than copper.
(iv) is an insulator of electricity.
See Answer(ii) generates more heat for a given current.
6. Electric heating devices (like an electric heater or stove) are often considered more convenient than traditional heating methods (like burning firewood or charcoal). Give reason(s) to support this statement considering societal impact.
See AnswerThey are smokeless and clean compared to firewood or charcoal.
Easy to operate and control (just switch ON/OFF).
They are more efficient because energy directly converts into heat.
They save time and effort and are safer for health and the environment.
7. Look at Fig. 4.4a. If the compass placed near the coil deflects: (i) Draw an arrow on the diagram to show the path of the electric current.. (ii) Explain why the compass needle moves when current flows. (iii) Predict what would happen to the deflection if you reverse the battery terminals.
See Answer(i) Drawing an arrow to show the path of current → (From positive terminal of the battery to negative).
(ii) The compass needle moves because the current carrying coil produces a magnetic field which affects the compass.
(iii) If battery terminals are reversed, the direction of current reverses, so the deflection of compass needle also reverses.
Class 8 Science Curiosity Chapter 4 Question 8, 9 and 10
8. Suppose Sumana forgets to move the switch of her lifting electromagnet model to OFF position (in introduction story). After some time, the iron nail no longer picks up the iron paper clips, but the wire wrapped around the iron nail is still warm. Why did the lifting electromagnet stop lifting the clips? Give possible reasons.
See AnswerThe cell/battery has become weak or exhausted, so it cannot provide enough current to make the electromagnet strong.
However, the weak current still produces some heating in the wire, making it warm, even though it is not strong enough to lift clips.
9. In Fig. 4.11, in which case will the LED glow when the switch is closed?
See AnswerCase (a): Iron nail + Lemon juice + Copper strip → LED will glow (because lemon juice acts as an electrolyte).
Case (b): Iron nail + Pure water + Copper strip → LED will not glow (pure water is a poor conductor).
10. Neha keeps the coil exactly the same as in Activity 4.4 but slides the iron nail out, leaving only the coiled wire. Will the coil still deflect the compass? If yes, will the deflection be more or less than before?
See AnswerYes, the coil will still deflect the compass because a current carrying coil produces a magnetic field.
But the deflection will be less because without the iron core the electromagnet is weaker.
Class 8 Science Curiosity Chapter 4 Question 11
11. We have four coils, of similar shape and size, made up from iron, copper, Aluminium and Nichrome as shown in Fig. 4.12.
When current is passed through the coils, compass needles placed near the coils will show deflection.
(i) Only in circuit (a)
(ii) Only in circuit (a) and (b)
(iii) Only in circuit (a), (b), and (c)
(iv) In all four circuits
See Answer(iv) In all four circuits (Because all these materials are conductors and when current flows, they produce a magnetic effect).
