1. The problem is to find the frequency of a wave or oscillation. 2. Frequency ($f$) is defined as the number of cycles or oscillations per unit time. 3. The formula to find frequency is: $$f = \frac{1}{T}$$ where $T$ is the period, the time taken for one complete cycle. 4. Important rule: Frequency is the reciprocal of the period. 5. If you know the period $T$, simply take the reciprocal to find frequency. 6. For example, if the period $T = 0.5$ seconds, then frequency is: $$f = \frac{1}{0.5} = 2$$ 7. This means the wave oscillates 2 times per second. 8. Frequency is measured in Hertz (Hz), which means cycles per second. 9. If you have the number of oscillations $N$ in time $t$, frequency can also be calculated as: $$f = \frac{N}{t}$$ 10. Always ensure units of time are consistent when calculating frequency.