Question

When the number of turns in a coil is doubled without any change in the length of the coil, its self inductance becomes

• A. Four times
• B. Doubled
• C. Halved
• D. Unchanged

Answer 1

Answer: (A)

Four times

Answer 2

$L \propto N ^ { 2 }$ i.e. $\frac { L _ { 1 } } { L _ { 2 } } = \left( \frac { N _ { 1 } } { N _ { 2 } } \right) ^ { 2 } \Rightarrow L _ { 2 } = L _ { 1 } \left( \frac { N _ { 2 } } { N _ { 1 } } \right) ^ { 2 } = 4 L _ { 1 }$