a. Can you write the basic reason of resonance? Is there any role of natural frequency in this phenomenon or not?
An object free to vibrate . It vibrate at a specific rate called the object's natural, or resonant, frequency. The rate of the vibration i.e how many vibration in one second or frequency depends on the size, shape, and composition of the object. Vibration in object will strong when it is vibrating at a frequency equal to or nearly equal its natural frequency. This phenomenon is called resonance. Through resonance, a comparatively weak vibration in one object can cause a strong vibration in another.
let we have two functions
y=sin(x) and y=sin(.99x)
see graph of y=sin(x) and y=sin(.99x) ,both functions have nearly equal frequency,onw shown in red and other in green.These functions are showing resonance.