A convex mirror of focal length f forms an image of a distant object. The image is MCQ with Answer and Explanation

Explanation:
Hydrogen fusion to helium releases energy.

Explanation:
p = m v = 5 × 2 = 10 kg m/s. Direction same as velocity. Momentum vector. Unit kg·m/s.

Explanation:
LED (Light Emitting Diode) works on electroluminescence: when electrons recombine with holes in a semiconductor junction, energy is released as photons. This is distinct from incandescence (heating filament, like bulbs), fluorescence (absorb UV, emit visible), or heating effect. Memory aid: 'LED = semiconductor light emission; no filament'. This modern application question tests knowledge of everyday physics, common in competitive exams. Always link device to underlying phenomenon: LED (electroluminescence), laser (stimulated emission), solar cell (photovoltaic effect).