Question

Find the time by alternating current to attain zero from peak value. The frequency of alternating current is 50Hz.

Answer 1

Hint: The current due to alternating current goes from peak positive value to peak negative value and then back to peak positive value. . The time taken for the wave to complete a cycle and go from peak positive to peak negative and back to peak positive is called the time period of the wave. The number of times the wave completes full cycles in a second is called frequency. The time taken for the wave to go from peak positive to 0. This change is one-fourth of the complete cycle of the wave.
Formula Used:
\[T=\dfrac{1}{f}\]

Complete answer:
Alternating current is a form of electric current that reverses its direction periodically. The current due to alternating current goes from peak positive value to peak negative value and then back to peak positive value. This cycle of the alternating current makes a wave called sine wave.
Like any wave, an alternative current also has frequency and time period. The time taken for the wave to complete a cycle and go from peak positive to peak negative and back to peak positive is called the time period of the wave. The number of times the wave completes full cycles in a second is called frequency. Frequency and time period of a wave is related as
\[T=\dfrac{1}{f}\].
In the question, the frequency of the wave is given to be 50Hz. Then the time period of the wave will be
\[\begin{align}
  & T=\dfrac{1}{50} \\
 & \Rightarrow T=0.02s \\
\end{align}\]
So, the time taken for the wave to complete a cycle is 0.02 seconds.
Now we have been asked to calculate the time taken for the wave to go from peak positive to 0. This change is one-fourth of the complete cycle of the wave. So, the time taken will be.
\[\begin{align}
  & t=\dfrac{T}{4} \\
 & \Rightarrow t=\dfrac{0.02}{4} \\
 & \Rightarrow t=5\times {{10}^{-3}}s \\
\end{align}\]
So, the time by the alternating current to attain zero from peak value will be \[5\times {{10}^{-3}}\] seconds.

Note:
There are two types of current. Alternating current (AC) and direct current (DC). Alternating current flows in cycles and changes its direction periodically meanwhile direct current flows in the same direction for the entirety of the time. A battery generates a direct current and the current found in our regular household is an alternating current.