When a coil is connected across a 20 V dc supply, it draws a current of 5 A. When it is connected across $20 \mathrm {~V} , 50 \mathrm {~Hz}$ ac supply, it draws a current of 4 A. The self inductance of the coil is $\_\_\_\_$ mH. (Take $\pi = 3$)
When a coil is connected across a 20 V dc supply, it draws a current of 5 A. When it is connected across $20 \mathrm {~V} , 50 \mathrm {~Hz}$ ac supply, it draws a current of 4 A. The self inductance of the coil is $\_\_\_\_$ mH. (Take $\pi = 3$)