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प्रश्न
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उत्तर
Four components of an electrical circuit
(i) Cell 
(ii) A load (bulb) 
(iii) Key 
(iv) Connecting wire 
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संबंधित प्रश्न
Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?
What is the SI unit of (i) electric energy, and (ii) electric power?
Define watt. Write down an equation linking watts, volts and amperes.
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?
1Kwh =`( 1 "volt "xx 1 am pere xx.............)/1000`
Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance.
State three factors on which the heat produced in a metallic wire due to passage of current in it depends.
Name two common material used for heating elements.
Find the energy released by a current of 0.25 amperes flowing through a heater for 5 minutes. The p.d. is 230 V.
A family uses 8 kW of power. Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
