Microwave oven heats food by MCQ with Answer and Explanation

Explanation:
Thermionic emission: heat supplies energy to overcome work function.

Explanation:
Micro (μ) denotes 10⁻⁶ in SI system. Nano = 10⁻⁹, pico = 10⁻¹², milli = 10⁻³. Standard prefixes: kilo(10³), milli(10⁻³), micro(10⁻⁶), nano(10⁻⁹). Memory aid: 'Micro = millionth; μm = micrometer = 10⁻⁶ m'. Frequently tested for unit conversion proficiency in competitive exams.

Explanation:
Additive primary: RGB.