Advertisements
Advertisements
प्रश्न
Compare the power used in the 2 Ω resistor in each of the following circuits:
- a 6 V battery in series with 1 Ω and 2 Ω resistors
- a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
उत्तर
(i) Potential difference, V = 6 V
1 Ω and 2 Ω resistors are connected in series. Therefore, equivalent resistance of the circuit is
R = R1 + R2
= 1 + 2
= 3 Ω
current flowing in the circuit Is = `"V"/"R"`
= `6/3`
= 2 A
Since equal electric current flows through all the resistances connected in series,
Therefore, power consumed by a 2 Ω resistor P1 = (I1)2R
= (2)2 × 2
= 8 W
(ii) Here V = 4 V, R1 = 12 Ω
And R2 = 2 Ω
∴ The current flowing through different resistances connected in parallel is different but the potential difference between the ends remains the same.
Therefore, power consumed by a 2 Ω resistor P2 = `"V"^2/"R"`
= `(4 "V")^2/(2 Ω)`
= 8W
Therefore, the 2 Ω resistor will consume the same amount of electrical power in both cases.
i.e., P1 = P2
APPEARS IN
संबंधित प्रश्न
Name the quantity whose unit is (i) kilowatt, and (ii) kilowatt-hour.
An electric lamp is labelled 12 V, 36 W. This indicates that it should be used with a 1 V supply. What other information does the label provide?
An electric fan runs from the 230 V mains. The current flowing through it is 0.4 A. At what rate is electrical energy transferred by the fan?
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
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
An electric kettle is rated 2.5 kW, 250 V. Find the cost of running the kettle for two hours at Rs. 5.40 per unit.
A geyser is rated 1500 W, 250 V. This geyer is connected to 250 V mains. Calculate:
(i) the current drawn
(ii) the energy consumed in 50 hours, and
(iii) the cost of energy consumed at Rs. 4.20 per kWh
Two resistors A and B of 4 Ω and 6 Ω, respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate the power dissipated in each resistor.
State three factors on which the heat produced in a metallic wire due to passage of current in it depends.
Why is heating element wound on a long porcelain rod in a room heater.
What is ‘Rating’ of an electric appliance?
Give two precautious that you would take while putting off an electric switch.
How does the heat produced by die passage of current in a metallic wire depend on the current in the wire?
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate total current taken from the supply.
An electric lamp A of 40 W and another electric lamp B of 100 W are connected to 220 V supply. Calculate the ratio of their filament resistances?
An immersion rod having resistance of 50 Ω is connected to 220V main supply. Assuming that all the energy generated goes to heat the water, calculate the time taken to heat 5 kg water from 30°C to 100°C.
1 kWh = ____________
A conductor of 10 Ω is connected across a 6 V ideal source. The power supplied by the source to the conductor is ______.
