The frequency (f) of a simple pendulum is the number of oscillations it completes per second and is given by the formula: f = \(\frac{1}{2\pi}\)\(\sqrt{\frac{\text{g}}{\text{l}}}\) where l is the length of the string and g is the acceleration due to gravity. Because the length l is in the denominator, the frequency is inversely proportional to the square root of the length. Therefore, increasing the length results in a slower swing rate, effectively reducing the frequency.