Question

The equivalent inductance of two inductances is 2.4 henry when connected in parallel and 10 henry when connected in series. The difference between the two inductances is

• A. 2 henry
• B. 3 henry
• C. 4 henry
• D. 5 henry

Answer 1

Answer: (A)

2 henry

Answer 2

$L _ { S } = L _ { 1 } + L _ { 2 } = 10 \mathrm { H }$ ..... (i)

$L _ { P } = \frac { L _ { 1 } L _ { 2 } } { L _ { 1 } + L _ { 2 } } = 2.4 \mathrm { H }$ ..... (ii)

On solving (i) and (ii) L₁L₂ = 24 ..... (iii)

Also $\left( L _ { 1 } - L _ { 2 } \right) ^ { 2 } = \left( L _ { 1 } + L _ { 2 } \right) ^ { 2 } - 4 L _ { 1 } L _ { 2 }$

$\Rightarrow L _ { 1 } - L _ { 2 } = 2 H$