Advertisements
Advertisements
Question
Give Scientific reason
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc, an alloy such as Nichrome is used, not pure metals.
Advertisements
Solution
In the electric equipment producing heat, such as iron, electric heater, boiler, toaster etc., an alloy such as Nichrome is used, not pure metals because of the following reasons:
(i) Resistivity of Nichrome is more compared to pure metal.
(ii) Melting point of Nichrome is high as compared to pure metal.
(iii) Nichrome does not get oxidised when heated in air whereas metal does.
APPEARS IN
RELATED QUESTIONS
Why does the cord of an electric heater not glow while the heating element does?
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
When current is switched ‘on’ in a room heater, it ______.
The safety device based on the heating effect of electric current is called a ______.
What is nichrome? State its one use.
An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it?
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
These days when current in the circuit suddenly increases _______ switches are used.
What is the heating effect of electric current?
What is a short circuit?
What is overloading?
Live wire and neutral wires have a 220 V potential difference.
Name any two appliances which works on the phenomenon of heating effect of electric current.
Explain the heating effect of electric current.
Which of the following is correct?
An electric iron consumes energy at the rate of 420 W when heating is at the maximum rate and 180 W when heating is at the minimum rate. The applied voltage is 220 V. What is the current in each case?
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
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.
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
What is an electric fuse made up of?
Explain the working of an electric fuse.
It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.
______ wire is used in the filament of the bulbs.
The following is not a safety device.
Find the odd one out.
1 kWh is equal to ______.
In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.
| A | B | C | D |
![]() |
![]() |
![]() |
![]() |
In a set up the students coated iron nails with zinc metal and noted that, iron nails coated with zinc prevents rusting. They also observed that zinc initially acts as a physical barrier, but an extra advantage of using zinc is that it continues to prevent rusting even if the layer of zinc is damaged. Name this process of rust prevention and give any two other methods to prevent rusting.
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
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.




