Ohms Law
To make a current flow through a resistance there must be a voltage across that resistance. Ohm's Law shows the relationship between the voltage (V), current (I) and resistance (R). It can be written in three ways: V = I × R or I = V R or R = V I where: V = voltage in volts (V) I = current in amps (A) R = resistance in ohms ( ) or: V = voltage in volts (V) I = current in milliamps (mA) R = resistance in kilohms (k ) For most electronic circuits the amp is too large and the ohm is too small, so we often measure current in milliamps (mA) and resistance in kilohms (k ). 1 mA = 0.001 A and 1 k = 1000 . The Ohm's Law equations work if you use V, A and , or if you use V, mA and k . You must not mix these sets of units in the equations so you may need to convert between mA and A or k and . The VIR triangle V I R Ohm's Law triangle You can use the VIR triangle to help you remembe...