An electric iron rated 750 W is operated for 2 hours/day. How much energy is consumed by the electric iron for 30 days?
Define watt-hour. How many joules are equal to 1 watt-hour?
An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
Explain why, filament type electric bulbs are not power efficient.
Write an expression for the electrical power spent in flow of current through a conductor in terms of
(a) Resistance and potential difference, (b) current and resistance.
1Kwh =`( 1 "volt "xx 1 am pere xx.............)/1000`
A bulb with rating 250 V, 100 W is connected to a power supply of 220 V situated 10 m away using a copper wire of area of cross-section 5 mm2. How much power will be consumed by the connecting wires? Resistivity of copper = 1.7 × 10−8 Ωm
What does the unit kilowatt hour measure? Define it.
Define Kilo watt hour.
What are the two main systems of wiring commonly used in houses? Which of these systems mentioned by you is better and why?
An electric bulb is marked 100 W, 230 V. What does this mean?
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
An electric bulb is rated 240V-60W and is working at 100% efficiency.
(i) Calculate the resistance of bulb.
(ii) (a) Draw the circuit diagram.
(b) What is the rate of conversion of energy in each bulb?
(c) Total power used by the bulbs.
I ampere of current is passed through a resistor of resistance R ohm for time t second. Obtain expression for
(i) the electrical energy, and
(ii) the electrical power spent.
What is the resistance of an appliance rated at V volt, P watt?
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?
A torch bulb is rated at 3 V and 600 mA. Calculate it’s
