Conductors and Insulators - UNSOLVED PRACTICE SET
Chapter: Electric Charges and Fields | Topic: Conductors and Insulators
CONDUCTORS AND INSULATORS - UNSOLVED PRACTICE SET
Topic: Conductors and Insulators
Multiple Choice Questions
Q1. In conductors, electric current flows easily because:
- Electrons are tightly bound to the nucleus
- Free electrons are available for conduction
- Protons move freely
- Neutrons carry the current
Q2. Which of the following is an insulator?
- Silver wire
- Aluminium foil
- Glass rod
- Copper pipe
Q3. When a conductor is given some charge, the charge distributes itself:
- Uniformly throughout the volume
- Only on the outer surface
- Only at the center
- Randomly inside the conductor
Q4. The handle of an electrician's screwdriver is made of plastic because:
- Plastic is a good conductor
- Plastic prevents electric shock by acting as an insulator
- Plastic is cheaper than metal
- Plastic makes the tool lighter
Q5. In an insulator, the electrons are:
- Completely free to move
- Loosely bound and can move easily
- Tightly bound to their atoms
- Absent from the material
Q6. A charged body is brought near an uncharged conductor. The conductor:
- Remains unaffected
- Gets charged by conduction
- Shows redistribution of charges (induction)
- Loses all its electrons
Short Answer Questions
Q7. Why do electricians wear rubber gloves while working with high-voltage equipment? Explain in terms of conductors and insulators.
Q8. Distinguish between conductors and insulators on the basis of their electronic structure.
Q9. Why does a charged conductor lose its charge when connected to the Earth (grounding)?
Q10. Explain why metals are good conductors of electricity while wood is an insulator.
Q11. What happens when a positively charged rod is brought near an uncharged metallic sphere placed on an insulating stand? Draw a simple diagram to support your answer.
Q12. Give two examples each of conductors and insulators commonly found in a school science laboratory.
Long Answer Questions
Q13. Explain the difference between charging by conduction and charging by induction. Which method requires direct contact between the charged body and the conductor? Give one example of each from daily life.
Q14. Describe what happens when a charged body is brought near a conductor and then near an insulator. Why does the behavior differ in the two cases? Use diagrams if necessary.
Q15. A metallic sphere is placed on an insulating stand. A negatively charged rod is brought near (but not touching) the sphere.
(a) Describe the redistribution of charges on the sphere.
(b) What happens if the sphere is now touched by a person standing on the ground?
(c) What will be the final charge on the sphere if the rod is removed after grounding?
Numerical / Application-Based Problems
Q16. In your school science fair, you set up an experiment with three materials: a copper wire, a glass rod, and an aluminium strip. You connect each to a simple circuit with a battery and a bulb.
(a) Predict which materials will make the bulb glow and which will not. Give reasons.
(b) If you replace the glass rod with a graphite rod from a pencil, what do you observe? Explain why.
(c) Classify the following materials as conductors or insulators: rubber, silver, distilled water, tap water, mica, iron.
Q17. A hollow metallic sphere of radius 10 cm is given a charge of +20 ฮผC.
(a) Where does this charge reside on the sphere? Explain.
(b) What is the electric field inside the hollow sphere? Justify your answer.
(c) If the sphere is connected to the Earth by a conducting wire, what happens to the charge? Explain the process.
Q18. An uncharged conducting sphere of radius 5 cm is placed on an insulating stand. A positively charged rod with charge +8 ฮผC is brought near the left side of the sphere (without touching).
(a) Describe the charge distribution on the sphere when the rod is near it.
(b) If the right side of the sphere is now connected to the ground with a wire and then the wire is removed, what charge remains on the sphere?
(c) Calculate the magnitude of the induced charge on each side of the sphere before grounding.