Advertisements
Advertisements
प्रश्न
Establish the relation that heat produced in a metallic conductor due to the flow of current is V2t/R joules, where V is the potential difference across the ends of the conductor, R its resistance and t is the time in second for which current flows.
Advertisements
उत्तर
From the relation Q = Vit joule
Applying Ohm's law, V = iR
or i = V/R
Substituting the value of i, we get
Q = `"V" . "V"/"R" "t" = ("V"^2"t")/"R"` joule.
संबंधित प्रश्न
Define watt. Write down an equation linking watts, volts and amperes.
When a current I flows through a resistance R for time t, the electrical energy spent is given by:
(a) IRt (b) I²Rt (c) `IR^2t` (d) `I^2R ⁄t`
A current of 2 A is passed through a coil of resistance 75Ω for 2 minutes. (a) How much heat energy is produced? (b) How much charge is passed through the resistance?
A bulb marked 12 V, 24 W operated on a 12 volt battery for 20 minutes. Calculate:
(i) the current flowing through it, and
(ii) the energy consumed
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.
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 .
In an electric radiator or room heater, state with reason, why the porcelain tube wound with a nichrome wire is placed between the pole and principal focus of the parabolic concave reflector.
Which material is the calorimeter commonly made of? Give one reason for using this material.
A house is provided with 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80 W, and one heater of 1.0 kW. Each day bulbs are used for 4h, fans for lOh, and heater for 2h. The voltage of mains is 220 V. Calculate:
(i) Maximum power of the circuit in the house,
(ii) maximum current capacity of the main fuse in the house,
(iii) the electrical energy consumed in a week,
(iv) cost of electricity consumed at 1.25 Rs. per kWh.
A torch bulb is rated at 3 V and 600 mA. Calculate it’s
- power
- resistance
- energy consumed if it is used for 4 hours.
