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प्रश्न
Explain the application of heating effect of electric current in an electric bulb with a diagram.
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उत्तर
- Electric bulb works on the principle of heating effect electric of current.
- The solenoid type coil of bulb has high resistivity and very high melting point.
- When current is passed through the bulb, solenoid type coil of bulb gets heated to high temperature (upto 3400 °C) and starts glowing.
संबंधित प्रश्न
An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.
Why is the tungsten used almost exclusively for filament of electric lamps?
The safety device based on the heating effect of electric current is called a ______.
Write Joule's law of heating.
What is nichrome? State its one use.
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
How does the resistance of a wire vary with its:
diameter?
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?
What is meant by the heating effect of current?
Name the material which is used for making the filaments of an electric bulb.
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
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.
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.
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?
In an electric bulb, coil of _______ metal is used.
Find the odd one out and give its explanation.
What is the heating effect of electric current?
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
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?
The heating element of an electric iron is made up of:
An electric component used as a safety device is electric circuit is ______.
Unscramble the following words:
SFEU
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
______ wire is used in the filament of the bulbs.
Copper wire offers very little ______ and does not get heated up quickly.
Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
An electric fuse is a wire made up of a material having ______ melting point.
The electric fuse works on the Joule heating principle.
1 kWh is equal to ______.
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?
Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three-pin plug, whereas an electric bulb can be connected with a two-pin plug?
She wrote: Three-pin connections reduce heating of connecting wires.
- Is her answer correct or incorrect? Justify.
- What is the function of a fuse in a domestic circuit?
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?
