The Calculation of Resistance in a Series Circuit

The current through two identical light bulbs connected in a series is 0.25 amps. The voltage across both bulbs is 100 volts. Find the resistance of a single light bulb.

Explanation:

According to Ohm's law, the current (I) passing through a metallic conductor is directly proportional to the potential difference (v) between its ends at constant temperature and pressure. Mathematically, E=IRt

Where E is the voltage across both bulbs, I is the current, Rt is the total equivalent resistance

E = 100V, I = 0.25amps Rt = R+R(since they are 2 identical bulbs in series, we will add them together)

Rt = 2R

Substituting these values in the formula to get R, we have;

100 = 0.25(2R)

100 = 0.5R

R = 100/0.5

R = 200ohms

The resistance of a single light bulb will be 200ohms.

Note that the unit of resistance is ohms