Advertisements
Advertisements
Question
The equation I2R seems to suggest that the rate of heating in a resistor is reduced if resistance decreases, whereas equation P = V2/R suggests just the opposite. How do you reconcile this problem?
Advertisements
Solution
There is no contradiction in the relation. It V is constant, on decreasing resistance, the current increases and so as P = I2R the same result we gets from equation P = V2/R.
RELATED QUESTIONS
Name the commercial unit of electric energy.
What is the maximum power in kilowatts of the appliance that can be connected safely to a 13 A ; 230 V mains socket?
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
How much energy does a 100 W electric bulb transfer in 1 minute?
(a) 100 J
(b) 600 J
(c) 3600 J
(d) 6000 J
Name the S.I. unit of electrical energy. How is it related to Wh?
An electric bulb marked 220 V, 100 W will get fused if it is made to consume 150 W or more. What voltage fluctuation will the bulb withstand?
The diagram shows a coil connected to a center zero galvanometerG . The galvanometer shows a deflect ion to the right when the north pole N of a powerful magnet is moved to the right as shown .

(i) Explain, why the defelct ion occurs in the galvanometer.
(ii ) State whether th e current in the coil is cl ockwise or anticl ockwise
when viewed from the end P.
(iii ) State th e observation in G when the coil is moved away from north
pole N of the magnet keeping the magnet stationary.
(iv)State the observation in G when both the coil and the magnet are
moved to right at th e same speed .
The resistance of filament of an electric heater is 500 Ω It is operated at 200V for 1 hour daily. Calculate the current drawn by the heater and the energy consumed in kWh, by the heater in a month of 30 days.
