CBSE Class 8 Science Electricity Magnetic and Heating Effects (Class 8 NCERT New) Quiz 2

1. Two conductors A and B carry the same current. Conductor A has twice the resistance of conductor B. Which conductor produces more heat in the same amount of time?

A Conductor B produces more heat B Conductor A produces more heat C Both produce the same amount of heat D Neither conductor produces heat

2. Magnetic field lines never intersect each other. What does this tell us about the magnetic field at any given point?

A The magnetic field has two directions at every point B The magnetic field has only one direction at any given point C The magnetic field is zero at every point D The magnetic field is always horizontal

3. In induction heating, a metal object is heated without direct contact with a heat source. Which principle is this based on?

A Thermal conduction through air B Electromagnetic induction causing eddy currents in the metal C Convection currents in the surrounding medium D Direct radiation from a magnetic field

4. A fuse wire is designed to melt and break the circuit when the current exceeds a safe limit. Which property of the fuse wire makes it suitable for this purpose?

A High melting point and low resistance B Low melting point and high resistance C High melting point and high resistance D Low melting point and low resistance

5. Where are magnetic field lines closest together around a bar magnet, and what does this indicate?

A At the center of the magnet, indicating zero field strength B Near the poles, indicating the field is strongest there C In the middle of the magnet, indicating maximum field strength D Far away from the magnet, indicating a uniform field

6. An electric heater uses a nichrome wire as its heating element. Why is nichrome preferred over copper for this purpose?

A Nichrome has lower resistance than copper B Nichrome has a high melting point and high resistance, making it suitable for heating C Nichrome is a better conductor of electricity than copper D Nichrome is cheaper and easier to obtain than copper

7. How does increasing the current through an electromagnet affect the force it can exert on a magnetic material?

A The force decreases as current increases B The force increases as current increases C The force is unaffected by the current D The force first increases then decreases

8. A student places a compass near a current-carrying wire. The compass needle deflects. What does this observation demonstrate?

A Electric current produces heat only B Electric current produces a magnetic field around the wire C The compass is broken D The wire is made of a magnetic material

9. In induction heating, why does a non-magnetic material like aluminum still get heated even though it is not strongly attracted to magnets?

A Aluminum absorbs heat from the surrounding air B Eddy currents are induced in aluminum due to the changing magnetic field, generating heat through resistance C Aluminum has a very low melting point, so it heats up easily D Aluminum reflects the magnetic field, which generates heat

10. A student has two wires of the same material and length. Wire X has a cross-sectional area twice that of Wire Y. Both carry the same current for the same time. Using the relationship , which wire produces more heat and why?

A Wire X produces more heat because it has greater area B Wire Y produces more heat because it has higher resistance due to smaller cross-sectional area C Both wires produce the same heat because they are made of the same material D Wire X produces more heat because it allows more current to flow