The part of the electromagnetic spectrum used in remote controls is MCQ with Answer and Explanation

Explanation:
The loudness level in decibels is calculated as L = 10 * log10(I / I0). If intensity I becomes 100I, the new level L' = 10 * log10(100I / I0) = 10 * [log10(100) + log10(I / I0)] = 10 * [2 + L/10] = 20 + L. Therefore, the loudness explicitly increases by 20 dB.

Explanation:
Geostationary satellite has orbital period equal to Earth's rotation (24 hours) and orbits in equatorial plane in same direction. It appears stationary from Earth's surface. Altitude about 36,000 km. Used for communication.

Explanation:
Sound travels to cliff and back. Total distance = speed × time = 340 × 2 = 680 m. So distance to cliff = 680/2 = 340 m. Use formula d = (v × t)/2. Time for round trip. Minimum distance for echo 17 m (approx) for 0.1 s persistence.