Common household electric current is called alternating current because the current alternates direction within the wires. The voltage V in a typical 115-volt outlet can be expressed by the function V(t)=163 sin wt Upper V left parenthesis t right parenthesis equals 163 sine omega t

,

where omega=w

is the angular speed (in radians per second) of the rotating generator at the electrical plant and t is the time measured in seconds. It is essential for electric generators to rotate at precisely 60 cycles per sec.

How many times does the current oscillate in 0.30

sec?__times

To know how many times does the current oscillates in the given time, you take into account that the number of oscillation can be calculated by using the following expression:

[tex]n=ft[/tex] (1)

f: frequency of the oscillation of the current

t: time = 0.30s

The frequency is the number of cycles per second, that is, f = 60 cycles/s

You replace the values of f and t in the equation (1):

[tex]n=(60\frac{cycles}{s})(0.30s)=18\ cycles[/tex]

In 0.30s the current oscillates 18 times