Advertisements
Advertisements
प्रश्न
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Advertisements
उत्तर
- Copper and aluminium are excellent electrical conductors.
- Since the resistance of copper and aluminium is very low, the amount of heat generated while carrying an electric current through them is also low.
Therefore, copper or aluminium wires are used for electricity transfer.
APPEARS IN
संबंधित प्रश्न
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?
What property of the filament wire accounts for this difference?
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:
- the total current taken from the supply
- the resistance of each heater and
- the energy supplied in kWh to the three heaters in 5 hours.
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Identify the figure and give its use.

Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on the factors stated by you.
Name any six domestic appliances based on the heating effect of electric current.
Answer the following question:
what is the heating effect of the electric current? state any four applications of it?
Compute the heat generated while transferring 96000 coulombs of charge in two hours through a potential difference of 40 V.
The electricity bill specifies the usage in _______.
These days when current in the circuit suddenly increases _______ switches are used.
Which of the following substance contracts on heating?
What is overloading?
Live wire and neutral wires have a 220 V potential difference.
Name some devices that run using heat effect of electric current
Name any two appliances which work under the principle of heating effect of current.
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
Your teacher has shown you the following activity.

Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in the following figure. The current flowing in both the circuits is the same.
- Will the heat produced in both cases be equal? Explain.
- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.

An MCB can be used instead of a fuse in an electrical circuit.
Explain the working of an electric fuse.
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
What is a trip switch?
What is the heating effect of electric current?
Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.
An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.
An electric iron is rated 220 V, 2 kW. If the iron is used for 3h daily find the cost of running it for one week if it costs ₹ 4.25 per kWh.
