Question

In a series LCR circuit, resonance occurring at 105Hz. At that time, the potential difference across the 100 resistance is 40V while the potential difference across the pure inductor is 30v. The inductance L of the inductor is equal to

• A. $2.0\times {10}^{-4}$
• B. $3.0\times {10}^{-4}$
• C. $1.2\times {10}^{-4}$
• D. $2.4\times {10}^{-4}$

Answer 1

The correct option is C $1.2\times {10}^{-4}$

In a series LCR circuit, resonance occurring at 105Hz. At that time, the potential difference across the 100 resistance is 40V while the potential difference across the pure inductor is 30v. The inductance L of the inductor is equal to

$Current\left(i\right)=\frac{V_r}{R}=\frac{100}{40}=2.5A$

the inductor value is $V_L=i\ast \left(wL\right)$

$L=\frac{30}{2.5\ast 2\ast \pi \ast 105}=1.2\ast {10}^{-4}H$