CXC - Caribbean Examinations Council Physics: Electricity and Magnetism Questions and Answers

Question 1

Which of the following I-V graphs correctly represents the behavior of an ohmic conductor, such as a fixed resistor at constant temperature?

Accepted Answer

A straight line passing through the origin with a constant positive gradient.

Answer

A curved line starting from the origin with a decreasing gradient.

Answer

A horizontal line indicating constant current regardless of voltage.

Answer

A straight line that does not pass through the origin.

Question 2

A student builds an electromagnet by wrapping a copper wire around an iron nail and connecting it to a battery. Which of the following changes would be MOST effective in increasing the strength of the electromagnet?

Accepted Answer

Increasing the number of turns in the coil around the nail.

Answer

Replacing the iron nail with a wooden dowel.

Answer

Decreasing the number of turns in the coil.

Answer

Using a battery with a lower voltage.

Question 3

A household appliance is rated at 1200 W and is designed to operate on a 240 V supply. What is the correct current drawn by the appliance when it is operating normally?

Accepted Answer

5.0 A

Answer

0.2 A

Answer

288,000 A

Answer

20 A

Question 4

Two resistors, one with a resistance of 6 Ω and the other with 3 Ω, are connected in parallel to a 12 V battery. What is the total equivalent resistance of the circuit?

Accepted Answer

2 Ω

Answer

9 Ω

Answer

0.5 Ω

Answer

18 Ω

Question 5

A step-down transformer is used to convert a high input voltage to a lower output voltage. This is achieved because the secondary coil has:

Accepted Answer

fewer turns than the primary coil.

Answer

more turns than the primary coil.

Answer

the same number of turns as the primary coil.

Answer

a thicker wire than the primary coil.

Question 6

Which statement BEST describes the process of charging a neutral metal sphere by induction using a negatively charged rod?

Accepted Answer

The rod repels electrons in the sphere, the sphere is grounded allowing electrons to leave, and the ground is removed before the rod, leaving a net positive charge.

Answer

The rod touches the sphere, transferring negative charges to it.

Answer

The rod is brought near the sphere, and protons are attracted from the ground onto the sphere.

Answer

The rod attracts electrons from the sphere, causing it to become positively charged without needing a ground connection.