Question

A string of holiday lights has 15 bulbs with equal resistances. If one of the bulbs

is removed, the other bulbs still glow. But when the entire string of bulbs is
connected to a 120-V outlet, the current through the bulbs is 5.0 A. What is the
resistance of each bulb?

Answer 1

Resistance of each bulb = 360 ohms

Step-by-step explanation:

Let each bulb have a resistance r .

Since, even after removing one of the bulbs, the circuit is closed and the other bulbs glow. Therfore, the bulbs are connected in Parallel connection.

`(1)/(r(equivalent)) = (1)/(r1) + (1)/(r2) + + + + (1)/(r15)`

`(1)/(r(equivalent)) = (15)/(r)`

R(equivalent) = r/15

Now, As per Ohms Law :

V = I * R(equivalent)

120 V = 5 A * r/15

r = 360 ohms