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.
Advertisements
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
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Name the commercial unit of electric energy.
What is the meaning of the symbol kWh? Which quantity does it represent?
In a house two 60 W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours everyday. Calculate the electric consumed in 30 days.
Electrical power P is given by the expression P = (Q × V) ÷ time. What do the symbols Q and V represent?
State and define the household unit of electricity.
What does the unit kilowatt hour measure? Define it.
What are the two main systems of wiring commonly used in houses? Which of these systems mentioned by you is better and why?
Mention three uses of the carbon arc.
What is the order of current drawn by appliances connected to the ‘light circuit’ of a household?
How does the heat produced by die passage of current in a metallic wire depend on the current in the wire?
An electric heater is rated 220 V, 550 W. Electrical energy is also measured in kWh. What do you understand by a kilo-watt-hour?
How can electric energy consumed by an electric appliance be calculated in kilowatt hour (kWh)?
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.
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.
1 mV is equal to:
A student wants to use an electric heater, an electric bulb and an electric fan simultaneously.
How should these gadgets be connected with the mains? Justify your answer giving three reasons.
