# ExpEYES

## Driven Pendulum, Resonance

### Oscillations

Oscillating systems transfer energy between two different storage modes, kinetic and potential in thecase of a pendulum. For LC circuit oscillators the energy is tranferred between the Capacitor and the Inductor. Every oscillating system has a natural resonant frequency, and it depends on the oscillating elements and the forces involved. For a pendulum, it is the length and the value of acceleration due to gravity.

### Driven Oscillations

Once started, the oscillations grdually die out due to the damping forces, unless some energy is supplied to it continuously. If the supplied energy is periodic and itâ€™s frequency and phase matches with the natural resonant frequency of the system, maximum energy transfer will occur and the amplitude of oscillations will drastically increase. This phenomena is called resonance.

• Construct a pendulum using two button shaped magnets and a strip of paper, as shown in the figure.
• Calculate the period using $T=2\pi\sqrt{\frac{L}{g}}$. For a 5cm long pendulum, the resonant frequency ($\frac{1}{T}$) is around 2.2 Hz.
• Connect the coil from SQ1 to Ground.
• Place the pendulum near the coil, as shown in the figure.
• Adjust the frequency of SQ1 to maximize the amplitude of oscillations.

Watch a Video of Driven Pendulum at Resonance