Frequency determines pitch: higher frequency ⇒ higher pitch (e.g., whistle vs drum). Loudness depends on amplitude; quality (timbre) on waveform/harmonics; speed on medium properties (density, elasticity). This is a fundamental characteristic of sound perception. Memory aid: 'Frequency → Pitch; Amplitude → Loudness'. Competitive exams often test these distinctions to identify misconceptions. Note: Speed of sound is independent of frequency in a given medium (non-dispersive for audible sound in air). Always link physical quantities to perceptual attributes correctly.
Explanation:
When a wave (like light or sound) changes mediums, its velocity changes due to the new medium's optical or mechanical density. Wavelength changes proportionally with velocity (v = fλ). However, frequency is determined solely by the source generating the wave and the energy of the photons/particles, and it remains absolutely constant.
Explanation:
LEDs are highly efficient, converting ~80-90% of electrical energy into light, rest heat. Incandescent bulbs ~10% efficient. LED long life, low power. Blue LED Nobel prize 2014.
Explanation:
Rainbow is formed by dispersion, refraction, and internal reflection of sunlight in water droplets. Two refractions and one internal reflection give primary bow. Secondary bow has two internal reflections. Not diffraction.
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