Electricity: Magnetic and Heating Effects — Class 8 MCQs with Answers
Class 8 CBSE Science · Chapter 4
72 practice questions · 24 Easy · 24 Medium · 24 Hard · Updated
Practise the most important Class 8 CBSE Science questions from Chapter 4, "Electricity: Magnetic and Heating Effects". You get 9 timed quizzes made from 72 NCERT-based MCQs, with answers and explanations. The questions are split into 24 Easy, 24 Medium and 24 Hard. Warm up on the basics, then move on to the exam-level questions that top scorers in CBSE Board exams get right.
To score well in "Electricity: Magnetic and Heating Effects", focus on clear concepts in physics, chemistry and biology basics. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This helps you stay accurate when time is short, just as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Electricity: Magnetic and Heating Effects, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 8 Science mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Electricity: Magnetic and Heating Effects — important questions & MCQs with answers (Class 8 Science)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation.
- Q1Easy
The flow of electric charge through a wire is called:
A.gravityB.electric current✓ CorrectC.soundD.only heatAnswer: B. electric current
Explanation: Electric current is defined as the flow of electric charge through a conductor; it is not defined by a single effect like heat, nor by unrelated phenomena such as gravity or sound.
- Q2Easy
When current flows through a wire, a nearby compass needle:
A.meltsB.disappearsC.gets heavierD.deflects (moves)✓ CorrectAnswer: D. deflects (moves)
Explanation: A current-carrying wire creates a magnetic field around it, which deflects a nearby compass needle — the magnetic effect of current, first seen by Oersted.
- Q3Easy
A coil of wire that becomes a magnet when current flows is an:
A.insulatorB.electromagnet✓ CorrectC.bulbD.fuseAnswer: B. electromagnet
Explanation: A coil of wire behaves like a magnet only while current flows through it — this current-dependent magnet is called an electromagnet.
- Q4Easy
When current flows through a conductor, the conductor gets:
A.colderB.longerC.hot (it heats up)✓ CorrectD.invisibleAnswer: C. hot (it heats up)
Explanation: Current flowing through a conductor makes it heat up as electrical energy converts to heat — the heating effect of current — not cool or lengthen it.
- Q5Easy
A device that provides current in a circuit is a:
A.switchB.battery (cell)✓ CorrectC.bulbD.compassAnswer: B. battery (cell)
Explanation: A cell or battery is the source that drives charge around a circuit, supplying the current that a switch, bulb, or compass cannot generate on their own.
- Q6Easy
The deflection of the compass needle shows that a current-carrying wire has a:
A.magnetic effect✓ CorrectB.tasteC.smellD.soundAnswer: A. magnetic effect
Explanation: A deflecting compass needle shows that the current-carrying wire has produced a magnetic field around itself — this is the magnetic effect of current.
- Q7Medium
In a simple circuit, current flows from the battery when the switch is:
A.open (OFF)B.brokenC.closed (ON)✓ CorrectD.missingAnswer: C. closed (ON)
Explanation: Closing a switch completes the conducting path, so current flows from the battery around the circuit; an open switch breaks that path entirely.
- Q8Medium
Oersted discovered the link between electricity and:
A.magnetism✓ CorrectB.soundC.lightD.gravityAnswer: A. magnetism
Explanation: Oersted's experiment with a compass needle near a current-carrying wire revealed the previously unknown link between electricity and magnetism.
- Q9Medium
The strength of an electromagnet depends on:
A.the colour of the wireB.the current and the number of turns of the coil✓ CorrectC.the day of the weekD.the length of the switchAnswer: B. the current and the number of turns of the coil
Explanation: An electromagnet's strength grows with both the current flowing through the coil and its number of turns — not with unrelated things like colour or the day.
- Q10Medium
A wire heats up when current flows because the current faces:
A.no oppositionB.a magnetC.a switchD.resistance (opposition to flow)✓ CorrectAnswer: D. resistance (opposition to flow)
Explanation: A wire heats up because its material offers resistance, opposing the flow of current, and that opposition converts some electrical energy into heat.
- Q11Medium
An LED will NOT light if it is connected:
A.with a batteryB.the wrong way round✓ CorrectC.in a closed circuitD.with a switchAnswer: B. the wrong way round
Explanation: An LED conducts current in only one direction, so it stays dark when connected the wrong way round, even inside an otherwise complete circuit.
- Q12Hard
A compass near a wire deflects only when the switch is ON. This shows the current produces a:
A.heat fieldB.sound waveC.magnetic field✓ CorrectD.only lightAnswer: C. magnetic field
Explanation: The needle deflects only while the switch is ON, showing the magnetic field exists solely because current is flowing — direct evidence of the magnetic effect of current.
- Q13Hard
Two electromagnets carry the same current, but one has more coil turns. The one with more turns will:
A.be weakerB.not workC.only get hotterD.be stronger and lift more clips✓ CorrectAnswer: D. be stronger and lift more clips
Explanation: More coil turns concentrate a stronger magnetic field for the same current, so the electromagnet with more turns is stronger and lifts more clips.
- Q14Hard
Two identical wires carry current for the same time, but one carries more current. The one with more current will be:
A.hotter✓ CorrectB.coolerC.the sameD.magnetic onlyAnswer: A. hotter
Explanation: Heat produced grows with the square of the current (H = I²Rt), so for the same time, the wire carrying more current becomes hotter.
Key concepts: Electricity: Magnetic and Heating Effects (Class 8 Science)
This chapter shows that an electric current does more than light a bulb — it has a magnetic effect and a heating effect. A current-carrying wire deflects a compass needle, which is how Oersted discovered that current creates a magnetic field. Winding the wire into a coil (with a soft iron core) makes an electromagnet whose strength grows with more turns and more current. Current also heats a conductor because of its resistance — the heating effect — which runs heaters, irons and bulbs, while the magnetic effect runs bells and motors.
- Electric current and circuit
- Electric current is the flow of charge around a closed circuit made of a cell, connecting wires, a switch and a component such as a bulb or LED.
- Conductor and insulator
- A conductor (like copper) lets current flow easily; an insulator (like plastic) does not, so it is used to cover wires safely.
- Magnetic effect of current
- A current-carrying wire deflects a nearby compass needle, showing that the current produces a magnetic field around itself — discovered by Hans Christian Oersted.
- Magnetic field
- The region around a current-carrying wire where the magnetic effect can be felt, for example by the deflection of a compass needle.
- Electromagnet
- A coil of wire, usually wound on a soft iron core, that becomes a magnet only while current flows and loses its magnetism when switched off.
- Strength of an electromagnet
- It increases with the number of turns of the coil, with the amount of current, and by using a soft iron core — a stronger electromagnet lifts more clips.
- Heating effect of current
- When current flows through a conductor it meets resistance, converting electrical energy into heat, so the conductor gets warm.
- Resistance
- The opposition a conductor offers to current; nichrome has a higher resistance than copper of the same size, so it heats up strongly while copper stays cool.
- What the heat depends on
- The heat produced in a wire depends on the current, the material, the thickness and length of the wire, and the time the current flows.
- Everyday applications
- The magnetic effect runs electric bells, motors, generators and crane electromagnets; the heating effect runs heaters, irons, toasters and glowing bulb filaments.
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Start this chapter free →Electricity: Magnetic and Heating Effects — FAQs
What are the key concepts in Class 8 Science Electricity: Magnetic and Heating Effects?+
This chapter shows that an electric current does more than light a bulb — it has a magnetic effect and a heating effect. A current-carrying wire deflects a compass needle, which is how Oersted discovered that current creates a magnetic field. Winding the wire into a coil (with a soft iron core) makes an electromagnet whose strength grows with more turns and more current. Current also heats a conductor because of its resistance — the heating effect — which runs heaters, irons and bulbs, while the magnetic effect runs bells and motors. Key ideas include Electric current and circuit, Conductor and insulator, Magnetic effect of current, Magnetic field, Electromagnet, Strength of an electromagnet.
What does Class 8 Science Chapter 4 (Electricity: Magnetic and Heating Effects) cover on XamBaaz?+
It has 72 NCERT-based MCQs on "Electricity: Magnetic and Heating Effects": 24 Easy, 24 Medium and 24 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams.
Are these "Electricity: Magnetic and Heating Effects" questions free to practise?+
Yes. Sign in with Google to practise "Electricity: Magnetic and Heating Effects" free. Full unlimited access is ₹999/year. One year from the day you pay. You stay in Class 8 till 31 March; on 1 April your account moves up to Class 9 and the rest of your year carries over. No chapter is charged separately.
How should I revise "Electricity: Magnetic and Heating Effects" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Electricity: Magnetic and Heating Effects" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Electricity: Magnetic and Heating Effects" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Electricity: Magnetic and Heating Effects (Class 8 Science)?+
The questions that matter most test Electric current and circuit, Conductor and insulator, Magnetic effect of current, Magnetic field, Electromagnet, Strength of an electromagnet. This page shows 14 solved important MCQs with answers and explanations. Sign in to practise all 72 questions on the chapter as timed quizzes.
Is there an online quiz for Electricity: Magnetic and Heating Effects?+
Yes — Class 8 Science Electricity: Magnetic and Heating Effects has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.