**Determination of the value of Gravity by the help of Simple Pendulum**

Theory: The acceleration due to gravity, g at a particular place can be determined by a simple pendulum. For this, the following equation is used.

**T = 2π √(L/g)**

Here, T = time period, L = effective length and g = acceleration due to gravity.

Now, squaring both sides of the above equation we get,

T^{2} = 4π^{2} (L/g)

or, **g = 4π ^{2} (L/T^{2})** … …. …. (1)

π is a constant and g is constant at a particular place. So, a particular value of L/T^{2} will be found at that place and by putting the average value of L/T^{2} in equation (1), we can determine the value of g.

**Experiment:** At first by a metre scale let the length of the thread of the simple pendulum, l is determined. Then by a slide callipers the diameter of the bob is measured from which the radius ‘r’ of the bob is calculated. The effective length, L = l + r is determined. Now, in the experimental site, the pendulum is allowed to oscillate so that the angular amplitude does not exceed 4^{0}. Time t for 20 complete oscillations is taken by a stop-watch. The time period, T = t/20; is found out and square of it is calculated. Now, by changing the length of the pendulum time periods are found out for different effective lengths. T^{2} is found out in each came.