CBSE Class 8 Science Electricity Magnetic and Heating Effects (Class 8 NCERT New) Quiz 1

1. What is an electromagnet?

A A permanent magnet made of iron B A magnet created by passing electric current through a coil of wire C A magnet found naturally in the earth D A magnet made from copper alone

2. What happens to the magnetic field of an electromagnet when the electric current is switched off?

A The magnetic field becomes stronger B The magnetic field reverses direction C The magnetic field disappears D The magnetic field remains the same

3. Which of the following best describes magnetic field lines?

A Lines that show the path of electric current B Lines that represent the direction and strength of a magnetic field C Lines that show the flow of heat in a conductor D Lines that represent the path of electrons in a wire

4. What is the SI unit of electric current?

A Volt B Ohm C Ampere D Watt

5. According to Joule's Law of heating, the heat produced in a conductor is proportional to which of the following?

A The resistance only B The square of the current, resistance, and time C The voltage only D The length of the conductor only

6. Which of the following materials is the best thermal conductor?

A Wood B Plastic C Copper D Rubber

7. In which direction do magnetic field lines emerge from a bar magnet outside the magnet?

A From the south pole to the north pole B From the north pole to the south pole C Perpendicular to the magnet D In random directions

8. Which of the following is a common application of an electromagnet?

A A glass thermometer B An electric bell C A wooden ruler D A plastic comb

9. What does thermal conductivity measure?

A The ability of a material to conduct electricity B The ability of a material to transfer heat C The ability of a material to store magnetic energy D The ability of a material to reflect light

10. A wire carrying current is wound around an iron core to form an electromagnet. If the number of turns in the coil is doubled while keeping the current constant, what happens to the strength of the electromagnet?

A The strength decreases by half B The strength remains the same C The strength approximately doubles D The strength becomes four times greater