A-Level Physics 2 — Questions and Answers
Question 1: What is the SI unit of electric potential?
- Ampere
- Volt (Correct answer)
- Ohm
- Coulomb
Correct answer: Volt
The SI unit of electric potential is the volt (V), defined as one joule per coulomb (1 V = 1 J/C). It represents the energy per unit charge.
Question 2: In a nuclear reaction, what does the equation E = mc² represent?
- The kinetic energy of the nucleus
- The energy equivalent of mass, showing that mass and energy are interchangeable (Correct answer)
- The gravitational potential energy
- The binding energy per nucleon only
Correct answer: The energy equivalent of mass, showing that mass and energy are interchangeable
Einstein's mass-energy equivalence shows that mass can be converted to energy and vice versa. In nuclear reactions, the mass defect is converted to energy according to E = mc².
Question 3: What is the work-energy theorem as applied in Singapore A-Level Physics?
- Work done equals force times time
- The net work done on a body equals the change in its kinetic energy (Correct answer)
- Work done equals mass times acceleration
- Work is always conserved
Correct answer: The net work done on a body equals the change in its kinetic energy
The work-energy theorem states that the net work done by all forces on a body equals the change in its kinetic energy: W_net = ΔKE = ½mv² - ½mu².
Question 4: What is Faraday's law of electromagnetic induction?
- EMF is proportional to the current flowing
- The induced EMF is equal to the rate of change of magnetic flux linkage (Correct answer)
- The magnetic field is always constant
- EMF is proportional to the resistance of the circuit
Correct answer: The induced EMF is equal to the rate of change of magnetic flux linkage
Faraday's law states that the magnitude of the induced EMF equals the rate of change of magnetic flux linkage: EMF = -dΦ/dt. The negative sign (Lenz's law) indicates the direction opposes the change.
Question 5: What happens to the resistance of a metallic conductor as its temperature increases?
- Resistance decreases
- Resistance increases because increased thermal vibrations impede electron flow (Correct answer)
- Resistance stays the same
- Resistance first increases then decreases
Correct answer: Resistance increases because increased thermal vibrations impede electron flow
In metals, higher temperature causes greater lattice vibrations, which increase collisions with conduction electrons, thus increasing resistance. This is why metals have a positive temperature coefficient of resistance.
Question 6: What is the difference between a stationary wave and a progressive wave?
- Stationary waves transfer energy; progressive waves do not
- Stationary waves do not transfer energy; progressive waves transfer energy in the direction of travel (Correct answer)
- There is no difference
- Progressive waves have nodes and antinodes
Correct answer: Stationary waves do not transfer energy; progressive waves transfer energy in the direction of travel
A stationary wave is formed by the superposition of two identical progressive waves travelling in opposite directions. Unlike progressive waves, stationary waves do not transfer energy — they have fixed nodes and antinodes.
A-Level Physics 2
What is the SI unit of electric potential?