Advertisements
Advertisements
प्रश्न
Water in an electric kettle connected to a 220 V supply took 5 minutes to reach its boiling point. How long will it take if the supply voltage falls to 200 V?
Advertisements
उत्तर
P = `"V"^2/"R"`
Heat gained = `("V"^2)/"R" xx "t"`
`("V"_1^2/"R") xx "t"_1 = ("V"_2^2/"R") xx "t"_2`
t2 = `("V"_1/"V"_2)^2 xx "t"_1`
`= (220/200)^2 xx 300 = 363 "s"`
= 6.05 min
APPEARS IN
संबंधित प्रश्न
What is consumed using different electrical appliances, for which electricity bills are paid?
Which uses more energy: a 250 W TV set in 1 hour or a 1200 W toaster in 10 minutes?
Two resistors A and B of resistance 4 Ω and 6 Ω respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate: (i) the power supplied by the battery, (ii) the power dissipated in each resistor.
Write the SI units for:
(a) Electric current
(b) Potential difference
(c) Charge.
Define Kilo watt hour.
An electric current is passed through a metallic wire. The wire gets heated up. Give the reason. Is it possible to melt the wire by passing a heavy current?
Name two common material used for heating elements.
Household wiring for lamp connections can either be done in parallel or in series.Which one would you prefer? Give a reason for your answer.
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate the energy supply in kWh to the three heaters in 5 hour.
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]`
