If the period is T, what is the frequency relation?

• A. F = 1 / T
• B. F = T
• C. F = T / 2
• D. F = 2T

Answer: (A)

Frequency tells you how many cycles happen each second, so it’s the reciprocal of the period. If one cycle takes T seconds, there are 1/T cycles every second, which gives f = 1/T. In other words, frequency in hertz equals one over the period in seconds, and the period is the reciprocal of frequency (T = 1/f). The other forms would imply incorrect units or amounts for cycles per second.