Dear Jameelbhai sahab, If you get a frequency generator and a small speaker (approx 5 cm) and put the speaker face down on the glass(not in a case, just straight against it), change the frequency of the small speaker until it starts jumping and buzzing around on the glass the most. This will be your resonant frequency, when the power of the little speaker gives the most oscillations in the glass. Regards Cyrus

In physics, resonance is the tendency of a system (usually a linear system) to oscillate at larger amplitude at some frequencies than at others. These are known as the system's resonant frequencies (or resonance frequencies). At these frequencies, even small periodic driving forces can produce large amplitude oscillations.

Resonances occur when a system is able to store and easily transfer energy between two or more different storage modes (such as kinetic energy and potential energy in the case of a pendulum). However, there are some losses from cycle to cycle, called damping. When damping is small, the resonant frequency is approximately equal to a natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies.

Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, acoustic resonance, electromagnetic resonance, nuclear magnetic resonance (NMR), electron spin resona ...more

All in physics

An object exposed to its resonant frequency will vibrate in sympathy with the sound. The wavefronts pushing on the object will arrive at just the right time to nudge the object with greater and greater amplitude each cycle. A good analogy is pushing a friend on a swing. If you push at random times, you will not be able to get your friend moving very well; if you push at a specific time in each swing, the swings will get higher and higher.
The easiest way to find the resonant frequencies is to place the object next to a speaker and also place a microphone attached to an oscilloscope next to the object. Have the speaker play a tone at a given volume, and then without changing the volume slowly change the pitch (or frequency). If you watch the oscilloscope you will notice that at certain frequencies the amplitude of the wave, which is proportional to the volume of the sound being picked up by the microphone, will be greater than at surrounding frequencies. These are the resonant frequen ...more

A resonant frequency is a natural frequency of vibration determined by the physical parameters of the vibrating object.

Same frequency needs to resonate