A 120V, 60W lamp is to be operated on 220V ac supply mains. calculate the value of non inductive resistance that would be required to ensure that the lamp i...
A 120V, 60W lamp is to be operated on 220V ac supply mains. calculate the value of non inductive resistance that would be required to ensure that the lamp is run on correct value
Answer Details
When the voltage across a resistive load is increased, the power consumed by the load increases. In this problem, the voltage across the lamp is increased from 120V to 220V. This would cause an increase in power consumption, which may lead to the lamp being damaged. To prevent this from happening, a non-inductive resistor is connected in series with the lamp.
To calculate the resistance required, we can use the formula:
R = (V2 - V1)2 / P
Where:
V1 = initial voltage (120V)
V2 = final voltage (220V)
P = power (60W)
Substituting the values, we get:
R = (220V - 120V)2 / 60W
R = 10000 / 60
R = 166.67 Ω
Thus, a non-inductive resistance of approximately 167 Ω would be required to ensure that the lamp is run on the correct value. However, since none of the options match this value exactly, we would choose the option closest to the calculated value, which is 200 Ω.