The diagram above shows a circuit with the key k open. Calculate :
(i) the resistance of the circuit when the key k is open.
(ii) the current drawn from the cell when the key k is open.
(iii) the resistance of the circuit when the key k is closed.
(iv) the current drawn from the cell when the key k is closed.
An electric toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.
An electric bulb is rated 250 W, 230 V calculate:
(i) the energy consumed in one hour
(ii) the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains.
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:
(i) the total current taken from the supply
(ii) the resistance of each heater and
(iii) the energy supplied in kWh to the three heaters in 5 hours.
Calculate the current through a 60 W lamp rated for 250 V. If the line voltage falls to 200 V, how is the power consumed by the bulb affected?
An electric iron is rated at 750 W, 230 V. Calculate the electrical energy consumed by the iron in 16 hours .
A geyser is rated 1500 W, 250 V. This geyer is connected to 250 V mains. Calculate:
(i) the current drawn
(ii) the energy consumed in 50 hours, and
(iii) the cost of energy consumed at Rs. 4.20 per kWh