Physics MDCAT MCQs
Mechanics, electricity & modern physics MCQs
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Answer: Kirchhoff\'s loop rule states ΣV = 0 around any closed loop, based on conservation of energy.
Answer: By Malus\'s law: I = I₀ cos²θ = I₀ cos²45° = I₀ × (1/√2)² = I₀/2
Answer: The maximum order n is limited by d sin θ = nλ, where sin θ ≤ 1, so n ≤ d/λ.
Answer: Kirchhoff\'s junction rule states ΣI = 0 at any junction, based on conservation of charge.
Answer: Alpha particles are helium nuclei (⁴He²⁺) with mass number 4 and charge +2e.
Answer: Activity can be measured in Becquerel (SI), Curie, or Rutherford units. 1 Ci = 3.7 × 10^10 Bq.
Answer: Forward bias: p-side connected to positive terminal, n-side to negative, reducing the barrier potential.
Answer: Length contraction: L = L₀√(1-v²/c²). Moving objects appear shorter in the direction of motion.
Answer: Einstein\'s mass-energy equivalence: E = mc², where c is the speed of light.
Answer: Relativistic mass: m = m₀/√(1-v²/c²). Mass increases with velocity.
Answer: λ = h/√(2meV) = 1.227/√V nm. For V = 100, λ = 1.227/10 = 0.1227 nm ≈ 0.123 nm
Answer: In beta minus decay, a neutron converts to a proton, emitting an electron and antineutrino.
Answer: The energy needed to remove an electron from ground state (n=1) is 13.6 eV.
Answer: Bohr\'s quantization condition: L = nh/2π = nℏ, where ℏ = h/2π.
Answer: λ = ln2/t½. The decay constant and half-life are inversely related.
Answer: Wheatstone bridge is balanced when P/Q = R/S, making the galvanometer reading zero.
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Gamma rays are:
Answer: Gamma rays are high energy electromagnetic photons emitted during nuclear transitions.
Answer: Time dilation: Δt = Δt₀/√(1-v²/c²). Moving clocks run slower than stationary ones.
Answer: E = hf = hc/λ, where h is Planck\'s constant and f is the frequency of the photon.
Answer: KE_max = hf - φ, so maximum kinetic energy depends on the frequency of incident light, not its intensity.