Students can practice the best Class 8 Science MCQ and Electricity Magnetic and Heating Effects Class 8 Science Curiosity Chapter 4 MCQ Online Test with Answers for exam preparation.
Class 8 Science Chapter 4 Electricity Magnetic and Heating Effects MCQ
Electricity Magnetic and Heating Effects MCQ
Class 8 Science Chapter 4 MCQ Online Test
Question 1.
Which material inside a coil makes it a stronger magnet?
(a) Wood
(b) Plastic
(c) Iron
(d) Copper
Answer:
(c) Iron
Question 2.
What is an electromagnet?
(a) A permanent magnet made from iron
(b) A magnet made by passing electric current through a coil
(c) A wire that produces heat when current passes
(d) A device to measure electric current
Answer:
(d) A device to measure electric current
Question 3.
In which of the following situations is the heating effect of electric current not useful?
(a) In an electric kettle
(b) In an electric iron
(c) In a fuse wire
(d) In a mobile charger
Answer:
(d) In a mobile charger
Question 4.
Which of the following works on the magnetic effect of electric current? (Competency Based Que.)
Answer:
Question 5.
Which action will NOT increase the strength of the magnetic field around a coil?
(a) Increasing the number of coils
(b) Using a high resistance wire
(c) Increasing the current
(d) Placing an iron rod inside the solenoid
Answer:
(b) Using a high resistance wire
Question 6.
Which material is commonly used as a heating element in electric irons and toasters?
(a) Aluminium
(b) Copper
(c) Nichrome
(d) Steel
Answer:
(c) Nichrome
Question 7.
What happens to the amount of heat produced if the current in a wire is increased?
(a) It decreases
(b) It stays the same
(c) It increases
(d) It vanishes
Answer:
(c) It increases
Question 8.
Why should we not use damaged or thin wires in electric circuits at home?
(a) They look old
(b) They don’t fit in sockets
(c) They can overheat and cause fire
(d) They reduce the brightness of bulbs
Answer:
(c) They can overheat and cause fire
Question 9.
In a dry cell, which part acts as the positive terminal?
(a) Zinc casing
(b) Iron pin
(c) Carbon rod with metal cap
(d) Electrolyte paste
Answer:
(c) Carbon rod with metal cap
Question 10.
Ravi sets up an electromagnet using a coil of wire, a battery and an iron nail. He notices that when the coil has 10 turns, it lifts 4 paper clips. When he increases the number of turns to 20, the nail lifts 8 paper clips. Which of the following conclusions is correct? (Competency Based Que.)
(a) Reducing turns increases magnetism
(b) More turns increase the magnetic strength
(c) Electromagnets work better without nails
(d) Paper clips are not affected by magnetism
Answer:
(b) More turns increase the magnetic strength
Question 11.
Why should we avoid throwing used batteries in the regular trash?
(a) They contain paper and plastic
(b) They are still useful
(c) They contain harmful metals and chemicals
(d) They are very heavy
Answer:
(c) They contain harmful metals and chemicals
Question 12.
Why is a dry cell more suitable for everyday use than a Voltaic cell?
(a) It is heavier
(b) It is filled with water
(c) It is compact and easy to carry
(d) It can melt objects
Answer:
(c) It is compact and easy to carry
Question 13.
Which of the following combinations is used in a dry cell?
(a) Iron container and aluminium rod
(b) Plastic case and zinc plate
(c) Zinc container and carbon rod
(d) Copper rod and sulphuric acid
Answer:
(c) Zinc container and carbon rod
Question 14.
Priya connects a circuit with a nichrome wire and observes that it gets hot quickly. She repeats the activity with a copper wire of the same size and notices almost no heating.
What could be the most likely reason for this observation?
(a) Copper is heavier than nichrome
(b) Nichrome resists current more than copper
(c) Nichrome is a poor conductor
(d) Copper wire is not connected properly
Answer:
(b) Nichrome resists current more than copper
Question 15.
Ananya observes that a rechargeable battery in her toy car takes longer to charge over time and discharges quickly.
Which of the following is the best explanation for this?
(a) Battery has stopped working due to low current
(b) Rechargeable batteries wear out after repeated use
(c) The charger is faulty and needs to be changed
(d) All batteries can only be used once
Answer:
(b) Rechargeable batteries wear out after repeated use
Question 16.
What is the function of the moist paste inside a dry cell?
(a) It prevents leakage
(b) It reduces heat
(c) It acts as an electrolyte
(d) It cools the battery
Answer:
(c) It acts as an electrolyte
Electricity Magnetic and Heating Effects Class 8 Assertion Reason Questions
The following questions consist of two statements. Assertion (A) and Reason (R). Answer the following questions by selecting the appropriate option given below
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Question 1.
Assertion (A) An electromagnet becomes stronger when an iron rod is inserted inside the coil.
Reason (R) Iron is a good conductor of electricity.
Answer:
(b) Both A and R are true but R is not the correct explanation of A.
Inserting an iron rod increases magnetic effect, but not because iron is a good conductor it’s because iron gets easily magnetised.
Question 2.
Assertion (A) A magnetic compass placed near a current-carrying wire shows deflection.
Reason (R) An electric current produces a magnetic field around the wire.
Answer:
(a) Both A and R are true and R is the correct explanation of A.
Current in the wire creates a magnetic field, which causes the compass needle to deflect.
Question 3.
Assertion (A) Lithium-ion batteries are widely used in mobile phones and electric vehicles.
Reason (R) Lithium-ion batteries are lightweight, rechargeable and can store a large amount of energy. (Competency Based Que.)
Answer:
(a) Both A and R are true and R is the correct explanation of A.
Lithium-ion batteries are commonly used because they are light, rechargeable, and hold a lot of energy.
Question 4.
Assertion (A) The heating effect of current depends on the material of the wire.
Reason (R) Copper wire produces more heat than Nichrome for the same current.
Answer:
(c) A is true but R is false.
Question 5.
Assertion (A) A coil with an iron core becomes a strong electromagnet.
Reason (R) Iron allows electric current to pass easily through the coil.
Answer:
(c) A is true but R is false.
Question 6.
Assertion (A) The heating effect of current depends on the material of the wire.
Reason (R) Copper wire produces more heat than Nichrome for the same current.
Answer:
(c) A is true but R is false.
Electricity Magnetic and Heating Effects Class 8 Case Based MCQ Questions
Question 1.
Chandu was curious about how electric stoves and room heaters work. One winter morning, he switched on a room heater and noticed its coil glowing red after some time. His father told him that the wire inside is made of a special material that gets hot without melting. Arjun also observed that if wires are too thin or damaged, they can overheat quickly and may cause sparks or fire. (Competency Based Que.)
(i) What causes the coil in a room heater to glow red?
(a) It reflects sunlight
(b) It produces light using chemical energy
(c) It gets heated due to electric current
(d) It absorbs heat from outside
Answer:
(c) It gets heated due to electric current
(ii) Why are damaged wires avoided in heating devices?
(a) They don’t fit properly
(b) They cool down quickly
(c) They may cause fire
(d) They are too expensive
Answer:
(c) They may cause fire
(iii) Which factor does not affect the amount of heat produced in a wire?
(a) Length of the wire
(b) Thickness of the wire
(c) Colour of the wire
(d) Amount of current flowing through it
Answer:
(c) Colour of the wire
Question 2.
Anaya connected a thin strip of aluminium foil between two terminals of a battery using wires and a switch. She touched the foil before switching on the current, it felt normal. When she switched it ON for 30 seconds, the foil became noticeably warm. She also observed that if she used a thicker foil, it heated less. Anaya concluded that the heating effect of electric current depends on the material and thickness of the wire.
(a) If Anaya had used nichrome wire instead of aluminium foil, what would likely happen?
(a) The wire would melt instantly
(b) The wire would not conduct electricity
(c) The wire would heat up but not melt
(d) The wire would cool down faster than foil
Answer:
(c) The wire would heat up but not melt. Nichrome has high resistance and can withstand high temperatures without melting, making it ideal for heating elements.
(b) What conclusion can be drawn from this experiment?
(a) Heating effect only works on iron
(b) Electric current has no heating effect
(c) Heating depends on wire type and current
(d) Batteries produce fire in all wires
Answer:
(c) Heating depends on wire type and current. The experiment shows that the heating of the wire changes depending on its thickness and material, and also on how much current flows. So, the heating effect is not the same for all wires and depends on these factors.
(c) If the number of batteries was increased, what change would Anaya most likely observe?
(a) The foil would cool faster
(b) No change in temperature
(c) The foil would heat up more quickly
(d) The circuit would stop working
Answer:
(c) The foil would heat up more quickly. More voltage leads to more current, which increases the heating effect.
Electricity Magnetic and Heating Effects Class 8 Fill in the blanks
1. A coil of wire that acts like a magnet when current flows through it is called an …………………. .
Answer:
electromagnet
2. ……………………….. wire is used in heaters because it gets hot without melting easily.
Answer:
nichorme
3. In an electromagnet, inserting an ………………………….. rod increases the magnetic strength.
Answer:
iron
4. When electric current flows through a wire, it creates a ………………………. field around it.
Answer:
magnetic
5. A Voltaic cell produces electricity using a ………………………….. reaction.
Answer:
chemical
6. The carbon rod in a dry cell acts as the ……………………….. terminal.
Answer:
positive
7. The strength of an electromagnet increases when current in the coil is …………………….. .
Answer:
increased
8. Recycling used lithium-ion batteries helps recover valuable materials and ……………………….. environmental harm.
Answer:
reduces
Electricity Magnetic and Heating Effects Class 8 True or False
1. Overheating of wires in electric circuits can lead to fire hazards.
Answer:
True
2. Electromagnets lose their magnetism when the electric current is switched off.
Answer:
True
3. Voltaic cells are commonly used in mobile phones and laptops today.
Answer:
False
4. Iron is a non-magnetic material and cannot be used in electromagnets.
Answer:
False
5. Used batteries should always be thrown in household dustbins.
Answer:
False
6. Lithium-ion batteries are commonly used in electric vehicles.
Answer:
True
7. Solid-state batteries are expected to be safer and long-lasting than current lithium-ion batteries.
Answer:
True
8. The zinc container in a dry cell acts as the negative terminal.
Answer:
True
9. In lithium-ion batteries, energy is produced through a mechanical reaction.
Answer:
False
Electricity Magnetic and Heating Effects Class 8 Match the following
Question 1.
Match the Column I with Column II.
| Column I | Column II |
| A. Overuse of a cell | 1. Can be reused after charging |
| B. Heating in wire | 2. Battery needs charging more frequently |
| C. Iron rod inside a coil | 3. Depends on current, time and resistance |
| D. Rechargeable battery | 4. Contains paste-like electrolyte |
| E. Dry cell | 5. Makes magnetic field stronger |
| F. Electromagnet | 6. Strength increases with more coil turns |
Answer:
A – 2, B – 3, C – 5, D – 1, E – 4, F – 6
| Column I | Column II |
| A. Overuse of a cell | 2. Battery needs charging more frequently |
| B. Heating in wire | 3. Depends on current, time and resistance |
| C. Iron rod inside a coil | 5. Makes magnetic field stronger |
| D. Rechargeable battery | 1. Can be reused after charging |
| E. Dry cell | 4. Contains paste-like electrolyte |
| F. Electromagnet | 6. Strength increases with more coil turns |
Question 2.
Match the Column I with Column II.
| Column I | Column II |
| A. Nichrome wire | 1. Found in smartphones and laptops |
| B. Compass needle deflection | 2. Heating effect of current |
| C. Lithium-ion battery | 3. Indicates magnetic field |
| D. Use of electromagnet in cranes | 4. For lifting scrap metal |
| E. Recycling old batteries | 5. Prevents environmental harm |
| F. Solid-state battery | 6. Uses solid electrolyte |
Answer:
A – 2, B – 3, C – 1, D – 4, E – 5, F – 6
| Column I | Column II |
| A. Nichrome wire | 2. Heating effect of current |
| B. Compass needle deflection | 3. Indicates magnetic field |
| C. Lithium-ion battery | 1. Found in smartphones and laptops |
| D. Use of electromagnet in cranes | 4. For lifting scrap metal |
| E. Recycling old batteries | 5. Prevents environmental harm |
| F. Solid-state battery | 6. Uses solid electrolyte |