Question

One `10V, 60W` bulb is to be connected to `100V` line. The required inductance coil has self-inductance of value `(f=50Hz)`
A. `0.052 H`
B. `2.42 H`
C. `16.2 mH`
D. `1.62 mH`

Answer 1

Correct Answer - A
Current through the bulb `i=P/V=60/10=6A`

`V=sqrt(V_(R)^(2)+V_(L)^(2))`
`(100)^(2)=(10)^(2)+V_(L)^(2) implies V_(L)=99.5` Volt
Also `V_(L)=iX_(L)=ixx(2pivL)`
`implies 99.5=6xx2xx3.15xx50xxLimplies L=0.052H`