Pakistan MCQs

Radioactive decay is a nuclear process.
Its probability is characterized by a decay constant and half-life.

After each half-life, the number of undecayed nuclei halves.
The process is statistical and exponential.

Fission can release neutrons that sustain a chain reaction.
It powers conventional nuclear reactors.

Fusion powers stars by converting a small amount of mass into energy.
It requires very high temperatures to overcome electric repulsion.

Photon energy is E=hf.
E=6.63×10^-34×5×10^14 = 3.315×10^-19 J.

Use Q=CV.
Q=5 μF×12 V = 60 μC.

Frequency is f=E/h.
F=4.0×10^-19 / 6.63×10^-34 ≈ 6.03×10^14 Hz.

Magnetic force is F=qvB for perpendicular motion.
F=2×3×4 = 24 N.

Einstein's photoelectric equation gives Kmax=Ephoton-φ.
Kmax=5-2 = 3 eV.

Force on a current-carrying wire is F=BIL.
F=3×4×0.5 = 6 N.

Use λ=h/p.
λ=6.63×10^-34 / 6.63×10^-24 = 1×10^-10 m.

Faraday's law gives emf=|ΔΦ/Δt| for one turn.
0.8/0.2 = 4 V.