O-Level Combined Science — Physics 4

Question 1

What is Ohm's Law?

Accepted Answer

V = IR

Answer

Ohm's Law states V = IR, where V is voltage (volts), I is current (amperes), and R is resistance (ohms).

Question 2

Which state of matter has a definite shape and volume?

Accepted Answer

Solid

Answer

Solids have a definite shape and volume because particles are closely packed in fixed positions with strong intermolecular forces.

Question 3

What energy transformation occurs in a solar cell?

Accepted Answer

Light to electrical

Answer

Solar cells (photovoltaic cells) convert light energy (from the sun) into electrical energy.

Question 4

An object is placed at the focal point of a converging lens. Where does the image form?

Accepted Answer

At infinity

Answer

When an object is placed at the focal point of a converging lens, the refracted rays are parallel and the image forms at infinity.

Question 5

What is the formula for calculating power?

Accepted Answer

P = E/t

Answer

Power = Energy/time (P = E/t), measured in watts (W). Also P = IV for electrical power.

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