Question

A string of 26 identical Christmas tree lights are connected in series to a 120 V source. The string dissipates 73 W. What is the equivalent resistance of the light string? Answer in units of Ω.

Answer 1

To solve this problem we will apply the concepts related to Ohm's law and Electric Power. By Ohm's law we know that resistance is equivalent to,

`R_(eq)= (V)/(I)`

Here,

V = Voltage

I = Current

While the power is equivalent to the product between the current and the voltage, thus solving for the current we have,

`P=VI \rightarrow I = (P)/(V)`

`I =0.608 A`

Applying Ohm's law

`R_(eq) = (120V)/(0.608A)`

`R_(eq) = 197.4\Omega`

Therefore the equivalent resistance of the light string is
`197.4\Omega`