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प्रश्न
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
उत्तर
- Electrical energy = Electrical power × time.
- For practical applications, devices consuming high electrical power are used over a period of time.
- This leads to heavy expenditure of electrical energy. To measure such value of energy unit joule is significantly small.
Hence, unit kWh is used in practice. Unit 1 kWh represents power of 1 kW used for 1 hour and equals 3.6 × 106 J.
संबंधित प्रश्न
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 ______.
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Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
Explain why, tungsten is used for making the filaments of electric bulbs.
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?
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(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
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If the current flowing through a fixed resistor is halved, the heat produced in it will become:
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?
An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at 'minimum heating' it consumes a power of 360 W but at 'maximum heating' it takes a power of 840 W. Calculate the current and resistance in each case.
Give a scientific reason.
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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.
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Explain the heating effect of electric current.
Which of the following is correct?
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.
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(c) Give a reason for your answer in (b).
Explain the working of an electric fuse.
Match the following
| 1. | Bulb | a. | Conductor |
| 2. | Electroplating | b. |
Insulator |
| 3. | Pure water | c. | Heating effect of current |
| 4. | Salt solution | d. | Chemical effect of current |
An electric fuse is a wire made up of a material having ______ melting point.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
Define the following:
Electrolysis and electrolyte
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
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.
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