Before starting this module, you should be able to:  When you complete this module, you should be able to: 

Topic 64.1 Basic Application of Ohm's Law for X_{L}
Ohm's Law applies directly to an inductor: V_{L} = I_{L}X_{L} where: V_{L} = voltage across the inductor 

For a certain inductor, I_{L} = 20 mA
and X_{L} = 420 W. What is
the voltage across this inductor? Ans: 8.4 V 
Solution: This is a straightforward application of Ohm's Law for X_{L}. V_{L} = I_{L}X_{L} 
What is the current through an inductive
reactance of 12 kW when the voltage across it is 12.6 V? Ans: 1.05 mA 
Solution: Given the values for X_{L} and V_{L}, use this form of Ohm's Law to solve for I_{L}: I_{L}= V_{L} / X_{L} 
The current through an inductor is 250 mA when
16 V is dropped across it. What is the value of X_{L}? Ans: 64 W 
Solution: Given the values for I_{L} and V_{L}, use this form of Ohm's Law to solve for X_{L}: X_{L}= V_{L} / I_{L} 
Topic 64.2 Ohm's Law when X_{L} is Not Known
R 
It follows that: V_{L} =2 
There aren't many electronics labs that
are equipped to measure the X_{L} of an inductor directly. Instead, X_{L}
is usually calculated from the value of the inductor and the frequency of the sine
waveform applied to it. So when you want to use Ohm's Law to determine the current of voltage across an inductor, you must first calculate the value of X_{L}, then solve for the current or voltage. Step 1: Calculate X_{L} = 2 Or you can combine the two equations to produce the single equation as shown on the left. 