The working of a refrigerator is based on MCQ with Answer and Explanation

Explanation:
Gamma rays highest frequency >10¹⁹ Hz, shortest wavelength. X-rays next. Radio lowest frequency. Frequency increases: Radio, microwave, IR, visible, UV, X-ray, gamma.

Explanation:
Using the second equation of motion for free fall: h = ut + ½gt². Since it is dropped, initial velocity (u) = 0. Time (t) = 4s, g = 10 m/s². The height h = 0 + ½(10)(4)² = 5 × 16 = 80 meters.

Explanation:
This is based on the conservation of angular momentum (L = Iω), where 'I' is the moment of inertia and 'ω' is angular velocity. When the boy extends his arms, mass moves further from the axis of rotation, increasing his moment of inertia (I). Since 'L' is conserved, an increase in 'I' must result in a decrease in angular velocity (ω).