"Several light bulbs each of resistance 1.25 Ω are connected in series across a 115 V power supply. If the current through the circuit is 2 A, what is the number of light bulbs in the circuit?

Ohm's Law: Ohm's law states that the current flowing through a conductor is directly proportional to its potential difference across its ends. At constant temperature and pressure. It can be expressed mathematically as

V = IR............. Equation 1

making R the subject of formula in equation 1

R = V/I.............. Equation 2

Where R = combined resistance of the several bulbs, V = potential difference, I = current through the circuit.

Given: V= 115 V. I = 2 A.

Substituting these values into equation 2,

R = 115/2

R = 57.5 Ω

Since the bulbs are connected in series,

Number of bulbs = combined resistance/resistance of each bulb

Number of bulbs = R/Rₙ...................... Equation 3

Where Rₙ = resistance of each bulb, R =combined resistance of the bulb.

Also given: Rₙ = 1.25 Ω, and R = 57.5 Ω

Substituting these values into equation 3

Number of bulbs = 57.5/1.25

Number of bulbs = 46 bulbs.

Therefore the number of bulbs = 46 bulbs