This instrument is called a spring scale.
It is diffraction
Explanation:
The opening is the aperture
To find:
The equation to find the period of oscillation.
Explanation:
The period of oscillation of a pendulum is directly proportional to the square root of the length of the pendulum and inversely proportional to the square root of the acceleration due to gravity.
Thus the period of a pendulum is given by the equation,

Where L is the length of the pendulum and g is the acceleration due to gravity.
On substituting the values of the length of the pendulum and the acceleration due to gravity at the point where the period of the pendulum is being measured, the above equation yields the value of the period of the pendulum.
Final answer:
The period of oscillation of a pendulum can be calculated using the equation,
I'm not too sure what your asking but here are two answers that may help.
The ear drum amplifies the vibrations.
The cochlea changes vibrations into electric signals.
Coals energy is affordable and it is easy to burn.