Question
We have 30 watt, 6 volt bulb which we want to glow by a supply of 120 V. What will have to be done for it?
Solution
Given,
Power of the bulb, P = 30 W
Potential of the bulb, V = 6 V
Supply voltage, V' = 120 V
Now, Resistance of the bulb,
Current that can be flown across the bulb,
Let R’ be the resistance used in series with the bulb to have a current of 5 A in the circuit.
Total resistance = R' + R = (R' + 1.2)
And so,
Current, I = V'/(R'+1.2)
That is, a resistance of 22.8 will have to be used in series with the lamp so as to supply a voltage of 120 V.
Power of the bulb, P = 30 W
Potential of the bulb, V = 6 V
Supply voltage, V' = 120 V
Now, Resistance of the bulb,
Current that can be flown across the bulb,
Let R’ be the resistance used in series with the bulb to have a current of 5 A in the circuit.
Total resistance = R' + R = (R' + 1.2)
And so,
Current, I = V'/(R'+1.2)
That is, a resistance of 22.8 will have to be used in series with the lamp so as to supply a voltage of 120 V.
