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प्रश्न
An electric filament lamp is connected to a supply of voltage higher than the recommended value. Give reasons, why compared with a normal performance, the lamp emits a brighter light and its life is shortened.
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उत्तर
The lamp will have the filament of a particular resistance. If it is connected to a supply of higher voltage, the heat energy produced in it will be more (since H = V2t/R), i.e., the filament will get more heated so it will glow more and the lamp will emit a brighter light. On the other hand, due to Excess heating, the filament may vaporize and so its life may shorten.
संबंधित प्रश्न
Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?
The table below shows the current in three different electrical appliances when connected to the 240 V mains supply:
| Appliance | Current |
| Kettle | 8.5 A |
| Lamp | 0.4 A |
| toaster | 4.8 A |
- Which appliance has the greatest electrical resistance? How does the data show this?
- The lamp is connected to the main supply by using a thin, twin-cored cable consisting of live and natural wires. State two reasons why this cable should not be used for connecting the kettle to the mains supply.
- Calculate the power rating of the kettle when it is operated from the 240 V mains supply.
- A main takes the kettle abroad where the mains supply is 120 V. What is the current is the kettle when it is operated from the 120 V supply?
What is the order of current drawn by appliances connected to the ‘light circuit’ of a household?
You are required to connect a bulb, a fan and a socket outlet to the mains in one set A and an air-conditioner and a refrigerator to the mains in other set B. Will you recommend the wire of same thickness and same insulation in both? explain your answer.
I ampere of current is passed through a resistor of resistance R ohm for time t second. Obtain expression for
(i) the electrical energy, and
(ii) the electrical power spent.
