GCSE Combined Science Physics — Questions and Answers
Question 1: What is the unit of measurement for electrical resistance?
- Volts (V)
- Amps (A)
- Ohms (Ω) (Correct answer)
- Watts (W)
Correct answer: Ohms (Ω)
Resistance is measured in ohms (Ω), named after Georg Ohm. Resistance is the opposition to the flow of current in a circuit. It can be calculated using Ohm's Law: R = V ÷ I (resistance = voltage ÷ current).
Question 2: A force of 200 N is applied to an area of 0.5 m². What is the pressure?
- 100 Pa
- 400 Pa (Correct answer)
- 200 Pa
- 250 Pa
Correct answer: 400 Pa
Pressure = force ÷ area = 200 ÷ 0.5 = 400 Pa. Pressure is measured in pascals (Pa). A smaller area with the same force creates a greater pressure, which is why sharp objects penetrate more easily.
Question 3: Which type of electromagnetic wave has the shortest wavelength?
- Radio waves
- Visible light
- Ultraviolet
- Gamma rays (Correct answer)
Correct answer: Gamma rays
Gamma rays have the shortest wavelength and highest frequency in the electromagnetic spectrum. The order from longest to shortest wavelength is: radio, microwave, infrared, visible light, ultraviolet, X-rays, gamma rays.
Question 4: What is the law of conservation of energy?
- Energy can be created from nothing
- Energy can be destroyed but not created
- Energy cannot be created or destroyed, only transferred between stores (Correct answer)
- Energy always increases in a closed system
Correct answer: Energy cannot be created or destroyed, only transferred between stores
The law of conservation of energy states that energy cannot be created or destroyed — it can only be transferred from one energy store to another. The total energy in a closed system always remains constant.
Question 5: A car accelerates from rest to 20 m/s in 5 seconds. What is its acceleration?
- 2 m/s²
- 4 m/s² (Correct answer)
- 5 m/s²
- 100 m/s²
Correct answer: 4 m/s²
Acceleration = change in velocity ÷ time = (20 - 0) ÷ 5 = 4 m/s². Starting 'from rest' means the initial velocity is 0 m/s. Acceleration tells us how quickly the velocity is changing.
Question 6: What happens to the current in a series circuit when more resistors are added?
- The current increases
- The current decreases (Correct answer)
- The current stays the same
- The current becomes alternating
Correct answer: The current decreases
In a series circuit, adding more resistors increases the total resistance. Since the supply voltage stays the same and V = IR, a higher resistance means a lower current flows through the circuit.
GCSE Combined Science Physics
What is the unit of measurement for electrical resistance?