Question

1 Hz is equal to
A) 1 cycle/sec
B) 4 cycle/sec
C) 2 cycles/sec
D) None of these

Answer 1

The hertz (Hz) is the Si unit for measuring the frequency of any periodic motion and how fast its periodicity is. It is also associated with waves and is also used to define the energy of photons via their frequency.

Complete step by step answer:
The hertz is defined as one cycle per second. The dimensions of hertz is that of the inverse of time so $[Hz] = {M^0}{L^0}{T^{ - 1}}$.
The unit of Hertz may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, or a human heart might be said to beat at $1.2{\text{ Hz}}$. This implies that the second hand of the clock moves one time per second while the human heartbeats $1.2{\text{ }}$ times in a second. Now obviously the human heart can only beat an integral number of times but the way we measure it is to calculate the number of times it beats in a few seconds and then divide that number by the number of seconds we measure it for which gives us the frequency of the heart.

Note: Problems can arise because the units of angular measure (cycle or radian) are omitted in SI units but are widely used in different fields of science such as waves and electromagnetism. This is because some quantities will measure displacement in terms of angular displacement of radians and hence even though angular velocity, angular frequency, and the unit hertz all have the dimension of the inverse of time, angular velocity and angular frequency are not expressed in hertz, but rather in an appropriate angular unit such as radians per second.