A lamp is rated “60 W, 120 V”. It is to be operated from a 240 V mains supply by connecting a suitable resistor in series with it.
(i) Find the resistance of the lamp at its rated conditions.
(ii) Determine the value of the series resistor required so that the lamp functions at its correct power when connected to 240 V.
(iii) Calculate the power dissipated in the series resistor when the circuit is working.
(iv) Compute the total power drawn from the 240 V supply and comment on the efficiency of using the lamp in this manner.
a. (i)
b. (ii)
c. (iii)
d. (iv)