O-Level Combined Science — Physics 3 — Questions and Answers
Question 1: What is the relationship between pressure and depth in a liquid?
- Pressure decreases with depth
- Pressure is independent of depth
- Pressure increases with depth (Correct answer)
- Pressure fluctuates with depth
Correct answer: Pressure increases with depth
Pressure in a liquid increases with depth because the weight of liquid above increases. P = ρgh.
Question 2: Which type of electromagnetic radiation has the longest wavelength?
- X-rays
- Ultraviolet
- Visible light
- Radio waves (Correct answer)
Correct answer: Radio waves
Radio waves have the longest wavelength in the electromagnetic spectrum, ranging from 1 mm to over 100 km.
Question 3: A pendulum completes 20 oscillations in 10 seconds. What is its frequency?
- 0.5 Hz
- 1 Hz
- 2 Hz (Correct answer)
- 4 Hz
Correct answer: 2 Hz
Frequency = number of oscillations ÷ time = 20 ÷ 10 = 2 Hz.
Question 4: What is the unit of electrical resistance?
- Volt
- Ampere
- Watt
- Ohm (Correct answer)
Correct answer: Ohm
The unit of electrical resistance is the Ohm (Ω), defined by Ohm's Law: V = IR.
Question 5: Which mirror produces a virtual, upright, and diminished image?
- Concave mirror
- Plane mirror
- Convex mirror (Correct answer)
- All mirrors
Correct answer: Convex mirror
A convex mirror always produces a virtual, upright, and diminished (smaller) image, regardless of object position.
Question 6: What is the acceleration due to gravity on Earth?
- 9.8 cm/s²
- 9.8 m/s² (Correct answer)
- 98 m/s²
- 0.98 m/s²
Correct answer: 9.8 m/s²
The acceleration due to gravity on Earth is approximately 9.8 m/s² (often approximated as 10 m/s² in calculations).
O-Level Combined Science — Physics 3
What is the relationship between pressure and depth in a liquid?