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प्रश्न
Explain the importance/uses of fuse wire.
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उत्तर
- Fuse is an important application of heating effect of electric current used in electric circuits.
- It protects circuits and appliances by stopping the flow of any excess electric current.
- If a current larger than the specific value flows through the circuit, the temperature of fuse wire increases. This melts the fuse wire and breaks the circuit.
- In summer season, when consumption of electrical power is huge in the evening due to home lighting, fan, air conditioner, use of electricity in shops etc, an excessive current is drawn from the transformer. If the capacity of the transformer is insufficient, its fuse wire melts, and the supply gets shut down.
संबंधित प्रश्न
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
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Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
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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? Give two applications of the heating effect of current.
The heat produced by passing an electric current through a fixed resistor is proportional to the square of:
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed
An electric fuse works on the:
(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
(d) heating effect of current
The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:
(a) x2 × y × z
(b) x × z × y2
(c) y × z2 × x
(d) y × z × x
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.
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What property of the filament wire accounts for this difference?
Which electric heating device in your home do you think have resistors which control the flow of electricity?
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- the resistance of each heater and
- the energy supplied in kWh to the three heaters in 5 hours.
Give a scientific reason.
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Identify the figure and give its use.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
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Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
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Write scientific reason.
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How can overloading be avoided?
Mark the correct choice
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- Reason: Three-pin connections reduce the heating of the connecting wires.
The heating element of an electric iron is made up of:
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- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
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(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
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Unscramble the following words:
SFEU
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An MCB can be used instead of a fuse in an electrical circuit.
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What is an electric fuse made up of?
Explain the working of an electric fuse.
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Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
The following is not a safety device.
Define the following:
Electrolyte
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.
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