Advertisements
Advertisements
प्रश्न
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?
Advertisements
उत्तर
| Filament of a light bulb | Connecting wire |
| The wire in the filament of a light bulb has a high resistance and a high melting point. So, it heats up without melting and glows when the current flows through it. | The connecting wire in a circuit has a low resistance and a low melting point. So, it does not heat up much when the current flows through it and thus does not glow. |
It is the high melting point of the filament wire that is accountable for this difference.
APPEARS IN
संबंधित प्रश्न
The safety device based on the heating effect of electric current is called a ______.
How does the resistance of a wire vary with its:
diameter?
Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
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?
The current passing through an electric kettle has been doubled. The heat produced will become:
(a) half
(b) double
(c) four time
(d) one-fourth
Write two devices based on the heating effect of electric current.
Right or wrong sentence.
Live wire and neutral wires have a 220 V potential difference.
Explain the application of heating effect of electric current in an electric bulb with a diagram.
Name some devices that run using heat effect of electric current
Heating effect of current is called ______
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
An electric cell produces electricity from the ______ ______ in it.
Name a few appliances which work on the basis of the heating effect of current.
A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.
Two students decided to investigate the effect of water and air on iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 ml of water. After a few days, the object were removed, dried and their masses were measured. The table shows their results.
| Student | Object | Mass of Object before Rusting in g |
Mass of the coated object in g |
| A | Nail | 3.0 | 3.15 |
| B | Thin plate | 6.0 | 6.33 |
What might be the reason for the varied observations of the two students?
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.
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.
The graph of voltage vs current for four different materials is shown below.
Which of these four materials would be used for making filament of bulb?
