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Question
An electric kettle has a heating element which is rated at 2 kW when connected to a 250 V electric supply. Calculate the
(a) Current which flows in the element when it is connected to a 250 V supply,
(b) Resistance of the filament,
(c) Heat produced in 1 minute by the element,
(d) Cost of running the kettle for 10 minutes a day for 30 days of the month, at the rate of Rs. 3.00 per unit.
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Solution
Given power P = 2k W = 2000 W, Voltage = 250 V
(a) Current I= `"P"/"V" = 2000/250 = 8 "A"`
(b) Resistance R = `"V"^2/"R" "t" = (250)^2/31.25 xx 60 = 1.2 xx 10^5 "Joules"`
(d)Energyconsumedperday=P x t=2 x `(10/60)` = 0.33 kWh
Energy consumed in 30 days= 0.33 x 30 = 10 kWh
Cost of running it @Rs3 per unit = 10 x 3 =Rs 30
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