The colour of light with minimum wavelength in visible spectrum is MCQ with Answer and Explanation

Explanation:
Resonance amplifies sound at natural frequency: instruments (guitar body), tuning forks (frequency standard). Memory tip: 'Resonance: musical instruments (amplify), tuning forks (calibration), avoid in bridges'. Wave application frequently tested in competitive exams.

Explanation:
Rutherford's gold foil experiment led to planetary model: electrons revolve around tiny positive nucleus. Bohr added quantized orbits. Thomson proposed plum-pudding model. Dalton atomic theory earlier.

Explanation:
A frequency of 50 Hz means there are 50 complete wave cycles per second. A single complete sinusoidal cycle consists of one positive half-cycle and one negative half-cycle. Therefore, the current reaches zero and reverses its direction exactly twice during each complete cycle. For 50 cycles, the current changes direction 50 * 2 = 100 times per second.