CBSE Class 8 Science Exploring Forces (Class 8 NCERT New) Quiz 7

1. Which of the following correctly describes an electromagnet?

A A permanent magnet made from iron ore B A magnet created by running electric current through a wire coiled around a core C A magnet that only works at very high temperatures D A natural magnet found in the Earth

2. What type of charge interaction causes two positively charged objects to repel each other?

A Gravitational force B Magnetic force C Electrical force D Normal force

3. Which of the following changes would most likely increase the strength of an electromagnet?

A Decreasing the number of wire coils around the core B Increasing the number of wire coils around the core C Using a plastic core instead of an iron core D Reducing the voltage of the battery

4. A student places two bar magnets near each other and observes that they attract. Which poles are facing each other?

A North and North B South and South C North and South D East and West

5. How does increasing the mass of two objects affect the gravitational force between them?

A The gravitational force decreases B The gravitational force remains unchanged C The gravitational force increases D The gravitational force becomes zero

6. A student builds an electromagnet using 10 coils of wire and a 1.5V battery. She then changes the battery to a 9V battery. What is the most likely result?

A The electromagnet becomes weaker B The electromagnet stops working C The electromagnet becomes stronger D The electromagnet's polarity reverses

7. Which model best demonstrates that a gravitational field exists even when objects are not in contact?

A Two objects touching and pushing each other B A diagram showing field lines extending outward from a massive object through empty space C A ball rolling on a flat surface D Two objects connected by a string

8. A student replaces the iron core of an electromagnet with a plastic core. What will most likely happen to the strength of the electromagnet?

A The strength will increase significantly B The strength will remain the same C The strength will decrease D The electromagnet will become a permanent magnet

9. Two electrically charged objects are moved farther apart. How does the electrical force between them change?

A The electrical force increases B The electrical force decreases C The electrical force stays the same D The electrical force becomes magnetic

10. A student wraps 20 coils of wire around an iron nail and connects it to a battery. The electromagnet picks up 5 paper clips. She then wraps 40 coils of wire around the same nail and uses the same battery. What is the most likely outcome?

A The electromagnet picks up fewer paper clips B The electromagnet picks up more paper clips C The electromagnet picks up the same number of paper clips D The electromagnet stops working