When the current in a coil changes from 2 amp. to 4 amp. in 0.05 sec., an e.m.f. of 8 volt is induced in the coil. The coefficient of self inductance of the coil is

Calcultion:
The formula for the induced e.m.f. in a coil is given by:

e = -L × (ΔI / Δt)

Where:

• e = induced e.m.f. = 8 V
• L = self-inductance of the coil (the quantity we need to find)
• ΔI = change in current = 4 A - 2 A = 2 A
• Δt = time taken for the change in current = 0.05 s

Now, substituting the known values into the equation:

8 = L × (2 / 0.05)

8 = L × 40

L = 8 / 40 = 0.2 henry

The coefficient of self-inductance of the coil is 0.2 henry.