When a coil is suddenly connected to a d.c. supply, if the initial rate of increase in current was maintained, it would reach its maximum value
A) instantaneously
B) in a period of time called a 'time constant'
C) in a period of time equivalent to five 'time constants'

Question

Quizplus · Accepted Answer

The sudden connection of a coil to a DC supply induces a back EMF, which opposes the increase in current. The rate of increase in current gradually reduces as the back EMF decreases, until the current reaches its maximum value in a period of time called a 'time constant'. Typically, it takes approximately 5 time constants for the current to reach 99.3% of its maximum value.

When a Coil Is Suddenly Connected to a D