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प्रश्न
An electrical appliance is rated 1500 W, 250 V. This appliance is connected to 250 V mains. Calculate:
(i) the current drawn,
(ii) the electrical energy consumed in 60 hours,
(iii) the cost of electrical energy consumed at Rs. 2.50 per kWh.
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उत्तर
(i) Since, W = V × i, But given that W = 1500, V = 250
Current, i = `"W"/"n"`
`= 1500/250 = 6` amperes
(ii) Energy consumed in 60 hours
`= ("Watts" xx "hours")/1000` kWh
`= (1500 xx 60)/1000 = 90` kWh
(iii) Cost of 90 kWh at Rs. 2.50/kWh = Rs. 90 × 2.50 = Rs. 225.00.
संबंधित प्रश्न
Define watt. Write down an equation linking watts, volts and amperes.
The commercial unit of energy is :
(a) watt
(b) watt-hour
(c) kilowatt-hour
(d) kilo-joule
An electric kettle for use on a 230 V supply is rated 3000 W. For safe working, the cable connected to it should be able to carry at least:
(a) 2 A
(b) 5 A
(c) 10 A
(d) 15 A
Name the S.I. unit of electrical energy. How is it related to Wh?
1kWh = …….. J
A current of 0.2 A flows through a wire whose ends are at a potential difference of 15 V.
calculate:
(i) the resistance of the wire and
(ii) the heat energy produced in 1 minute.
An electric iron rated 750 W is operated for 2 hours/day. How much energy is consumed by the electric iron for 30 days?
What changes in energy occur in an electric heater?
What is the commercial unit of electrical energy?
A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?
`[ρ_(Cu) = 1.7 xx 10_(Ωm)^-8, ρ_(Al) = 2.7 xx 10^-8 Ωm]`
