Advertisements
Advertisements
Question
What is meant by "electric power"?
Advertisements
Solution
The energy required per unit of time is called electrical power.
RELATED QUESTIONS
Name two safety devices which are connected to the live wire of a household electric circuit
State two factors on which the electrical energy consumed by an electrical appliance depends.
What is the meaning of the symbol kWh? Which quantity does it represent?
A 2 kWh heater, a 200 W TV and three 100 W lamps are all switched on from 6 p.m. to 10 p.m. What is the total cost at Rs 5.50 per kWh?
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 physical quality which is measured in
(i) Kw (ii) kWh
Distinguish between kilowatt and kilowatt-hour.
1Kwh =`( 1 "volt "xx 1 am pere xx.............)/1000`
An electrical appliance having a resistance of 200Ω is operated at 200 V. Calculate the energy consumed by the appliance in 5 minutes (i) in joules (ii) in kWh.
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
Two resistors A and B of resistance 4 Ω and 6 Ω respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate: (i) the power supplied by the battery, (ii) the power dissipated in each resistor.
An electric toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.
The diagram above shows a circuit with the key k open. Calculate :
(i) the resistance of the circuit when the key k is open.
(ii) the current drawn from the cell when the key k is open.
(iii) the resistance of the circuit when the key k is closed.
(iv) the current drawn from the cell when the key k is closed.
Fig . shows the essent ial features of a battery operated bell. The hammer strikes the gong when the swi tch is closed . State and explain the effect of using the following material successively to form the core.
(a) Plastic
(b) Steel
(c) Copper
Name the physical quantity which is measured in kW.
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 supplied by the battery.
What are the two main systems of wiring commonly used in houses? Which of these systems mentioned by you is better and why?
What changes in energy occur in an electric bulb?
A device is used to transform 12 V a.c. to 200 V a.c. What is the name of this device? Name the principle on which it works.
An electric bulb is marked 100 W, 230 V. What does this mean?
What is the function of the split rings in a d.c. motor?
Why is the electric power from the generating station transmitted at high voltage?
How does the heat produced by die passage of current in a metallic wire depend on the current in the wire?
What do you understand by ‘earthing’? What are the advantages of earthing in a household electric circuit? Explain, how it is done?
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.
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.
Find the energy released by a current of 0.25 amperes flowing through a heater for 5 minutes. The p.d. is 230 V.
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the current through the filament of the bulb.
An Electric bulb is marked 100 W, 230 V. What find the energy consumed by the bulb in one hour.
An Electric bulb is marked 100 W, 230 V. What how long would this lamp take to consume one unit of electricity?
1 mV is equal to:
If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.
A electric bulb is rate 220 V, 60 W. its electric cell resistance is nearly
A conductor of 10 Ω is connected across a 6 V ideal source. The power supplied by the source to the conductor is ______.
