A-Level Physics — Questions and Answers
Question 1: According to Newton's Second Law as taught in Singapore A-Level Physics, what is the relationship between force, mass, and acceleration?
- F = ma²
- F = ma (Correct answer)
- F = m/a
- F = m + a
Correct answer: F = ma
Newton's Second Law states that the resultant force acting on a body is equal to the product of its mass and acceleration: F = ma. This is the fundamental equation of dynamics.
Question 2: What is the principle of conservation of momentum?
- Momentum is always increasing
- The total momentum of a closed system remains constant if no external forces act on it (Correct answer)
- Momentum is only conserved in elastic collisions
- Momentum equals mass times velocity squared
Correct answer: The total momentum of a closed system remains constant if no external forces act on it
In a closed system with no external forces, the total momentum before an interaction equals the total momentum after. This applies to all collisions and explosions.
Question 3: What is the relationship between electric field strength (E) and potential difference (V) for a uniform field?
- E = V × d
- E = V/d (Correct answer)
- E = V²/d
- E = d/V
Correct answer: E = V/d
For a uniform electric field between parallel plates, E = V/d, where V is the potential difference and d is the separation between the plates.
Question 4: In the photoelectric effect studied in Singapore A-Level Physics, what determines whether electrons are emitted?
- The intensity of the light
- The frequency of the light must exceed the threshold frequency (Correct answer)
- The temperature of the metal surface
- The duration of light exposure
Correct answer: The frequency of the light must exceed the threshold frequency
Einstein's photoelectric equation shows that electrons are emitted only when the photon frequency exceeds the threshold frequency (f₀). Below f₀, no electrons are emitted regardless of intensity.
Question 5: What is the de Broglie wavelength of a particle?
- λ = h/E
- λ = h/p, where h is Planck's constant and p is momentum (Correct answer)
- λ = h × p
- λ = p/h
Correct answer: λ = h/p, where h is Planck's constant and p is momentum
The de Broglie wavelength is λ = h/p, where h is Planck's constant (6.63 × 10⁻³⁴ Js) and p is the momentum of the particle. This demonstrates wave-particle duality.
Question 6: What is simple harmonic motion (SHM) as defined in the Singapore A-Level syllabus?
- Motion with constant velocity
- Motion where the acceleration is proportional to displacement and directed towards a fixed point (Correct answer)
- Motion in a straight line with constant acceleration
- Motion in a circle at constant speed
Correct answer: Motion where the acceleration is proportional to displacement and directed towards a fixed point
SHM is defined as motion where the acceleration is proportional to the displacement from a fixed point (equilibrium) and always directed towards that point: a = -ω²x.
A-Level Physics
According to Newton's Second Law as taught in Singapore A-Level Physics, what is the relationship between force, mass, and acceleration?