Electricity Magnetic and Heating Effects Class 8 MCQ with Answers are designed to help students understand and revise important concepts related to the magnetic and heating effects of electric current. These multiple-choice questions cover topics such as electromagnets, magnetic effects of current, heating effect, electric cells, conductors, and everyday applications of electricity. The MCQs are useful for quick revision, practice, class tests, and exam preparation.
Electricity Magnetic and Heating Effects Class 8 MCQ with Answers
Conceptual Recall
Q. Who discovered that electric current produces a magnetic effect?
(a) Michael Faraday
(b) Hans Christian Oersted
(c) Isaac Newton
(d) James Clerk Maxwell
Answer: (b) Hans Christian Oersted
Explanation: In 1820, Oersted observed compass deflection near a current‑carrying wire.
Q. What is the region around a magnet or current‑carrying wire where its magnetic effect can be felt called?
(a) Magnetic domain
(b) Magnetic field
(c) Magnetic pole
(d) Magnetic circuit
Answer: (b) Magnetic field
Explanation: Compass deflection shows the presence of a magnetic field.
Q. When electric current flows through a conductor, part of the electrical energy is converted into:
(a) Light energy
(b) Heat energy
(c) Sound energy
(d) Mechanical energy
Answer: (b) Heat energy
Explanation: Opposition to current flow (resistance) causes heating effect.
Q. In a Voltaic cell, the rods partly dipped in the electrolyte are called:
(a) Conductors
(b) Electrodes
(c) Terminals
(d) Magnets
Answer: (b) Electrodes
Explanation: Electrodes are the metal rods that react with the electrolyte to produce electricity.
Q. Which scientist proved that electricity in a Voltaic cell comes from metals and electrolyte, not from the frog’s body?
(a) Luigi Galvani
(b) Alessandro Volta
(c) Michael Faraday
(d) James Maxwell
Answer: (b) Alessandro Volta
Explanation: Volta used saltwater-soaked paper instead of frog’s leg and still got current.
Q. In textbook activity, , if the compass north pole is attracted to end A of the coil, then end A is:
(a) North pole
(b) South pole
(c) Neutral
(d) East pole
Answer: (b) South pole
Explanation: Unlike poles attract; compass north pole → coil’s south pole.
Q. A coil connected to 4 cells produced more deflection in compass needles than with 1 cell. What does this show?
(a) Magnetic field decreases with more cells
(b) Magnetic field depends on current magnitude
(c) Magnetic field depends only on wire length
(d) Magnetic field depends only on material type
Answer: (b) Magnetic field depends on current magnitude
Explanation: More cells → more current → stronger electromagnet.
Q. A coil connected to 2 cells produced more heat than with 1 cell. What does this show?
(a) Heat produced is independent of current
(b) Heat produced depends on current magnitude
(c) Heat produced depends only on wire length
(d) Heat produced depends only on material type
Answer: (b) Heat produced depends on current magnitude
Explanation: More cells → more current → more heat generated.
Q. In a dry cell, which part acts as the negative terminal?
(a) Carbon rod
(b) Zinc container
(c) Metal cap
(d) Electrolyte paste
Answer: (b) Zinc container
Explanation: Zinc container is the negative terminal, carbon rod with metal cap is the positive terminal.
Q. In the lemon cell experiment, which part acts as the electrolyte?
(a) Copper wire
(b) Iron nail
(c) Lemon juice
(d) LED
Answer: (c) Lemon juice
Explanation: Lemon juice conducts electricity by allowing chemical reactions between electrodes.
Application-Based
Q. A crane operator uses a lifting electromagnet in a scrap yard. What happens when the current is switched OFF?
(a) The electromagnet becomes stronger
(b) The iron/steel objects are released
(c) The electromagnet turns into a permanent magnet
(d) The crane stops working
Answer: (b) The iron/steel objects are released
Explanation: Magnetic field disappears when current is stopped.
Q. A student wants to make a stronger electromagnet. Which step will help?
(a) Reduce the number of turns in the coil
(b) Use more cells in the battery
(c) Remove the iron core
(d) Use thinner wire with fewer loops
Answer: (b) Use more cells in the battery
Explanation: More cells → more current → stronger magnetic field.
Q. A nichrome wire gets warmer than a copper wire of the same size when current flows because:
(a) Nichrome has higher resistance
(b) Copper has higher resistance
(c) Nichrome is a poor conductor of heat
(d) Copper produces more heat
Answer: (a) Nichrome has higher resistance
Explanation: Higher resistance converts more electrical energy into heat.
Q. A student makes a lemon cell using copper wires and iron nails. The LED does not glow at first. What should the student do?
(a) Replace lemon with orange
(b) Reverse the LED connections
(c) Add more copper wires
(d) Remove the iron nails
Answer: (b) Reverse the LED connections
Explanation: LED glows only when connected with correct polarity.
Q. Why are dry cells more convenient than Voltaic cells for everyday use?
(a) They are larger in size
(b) They use a moist paste electrolyte instead of liquid
(c) They produce unlimited electricity
(d) They never get exhausted
Answer: (b) They use a moist paste electrolyte instead of liquid
Explanation: Paste electrolyte makes dry cells portable and safe.
Assertion–Reason
Q. Assertion (A): An electromagnet has two poles like a bar magnet.
Reason (R): The polarity of an electromagnet depends on the direction of current flow.
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A true, R false
(d) A false, R true
Answer: (a) Both A and R are true, R explains A
Explanation: Changing current direction reverses the poles of an electromagnet.
Q. Assertion (A): A freely suspended magnet rests along the north–south direction.
Reason (R): Earth itself behaves like a giant magnet.
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A true, R false
(d) A false, R true
Answer: (a) Both A and R are true, R explains A
Explanation: Earth’s magnetic field guides the magnet’s direction.
Q. Assertion (A): Household appliances like electric irons and kettles work on the heating effect of current.
Reason (R): Their heating elements convert electrical energy into heat energy.
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A true, R false
(d) A false, R true
Answer: (a) Both A and R are true, R explains A
Explanation: Heating elements glow red hot due to resistance heating.
Q. Assertion (A): Rechargeable batteries save money over time.
Reason (R): They can be recharged and reused multiple times.
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A true, R false
(d) A false, R true
Answer: (a) Both A and R are true, R explains A
Explanation: Recharging prevents wastage and repeated buying of new cells.
Q. Assertion (A): Lithium-ion batteries are widely used in modern devices.
Reason (R): They rely on metals like lithium and cobalt.
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A true, R false
(d) A false, R true
Answer: (a) Both A and R are true, R explains A
Explanation: Li-ion batteries are common in phones, laptops, and vehicles.
Case Study-Based
Q. During a science exhibition, Mohini saw a nail wrapped with wire connected to a battery. When the circuit was closed, the nail picked up paper clips. When the circuit was opened, the clips fell.
What does this experiment prove?
(a) Nail is a permanent magnet
(b) Electric current produces a magnetic effect
(c) Clips are non-magnetic
(d) Battery itself is a magnet
Answer: (b) Electric current produces a magnetic effect
Explanation: The nail became an electromagnet only when current flowed.
Q. Mohini saw a nail wrapped with wire connected to a battery at the science exhibition. When the circuit was closed, the nail picked up paper clips. When opened, the clips fell. What does this experiment prove?
(a) Nail is a permanent magnet
(b) Electric current produces a magnetic effect
(c) Clips are non‑magnetic
(d) Battery itself is a magnet
Answer: (b) Electric current produces a magnetic effect
Explanation: The nail became an electromagnet only when current flowed.
Q. In textbook activity, students connected a nichrome wire to a cell. They observed the wire was cool before switching ON, but warm after current flowed.
What conclusion can be drawn?
(a) Nichrome wire is a permanent heater
(b) Current produces a heating effect in conductors
(c) Wire becomes a magnet when heated
(d) Battery itself produces heat directly
Answer: (b) Current produces a heating effect in conductors
Explanation: Resistance in wire converts electrical energy into heat.
Q. Galvani observed a frog’s leg twitch when touched with copper and iron. Volta repeated the experiment using saltwater-soaked paper and still got current.
What conclusion did Volta draw?
(a) Electricity comes from the frog’s muscles
(b) Electricity comes from the metals and electrolyte
(c) Frog’s body is a permanent battery
(d) Saltwater destroys metals
Answer: (b) Electricity comes from the metals and electrolyte
Explanation: Volta proved that chemical reaction between metals and liquid generates electricity.
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