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प्रश्न
What do you mean by power rating of an electrical appliance? How do you use it to calculate
(a) the resistance of the appliance and
(b) the safe limit of the current in it, while in use?
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उत्तर
An electrical appliance such as electric bulb, geyser etc. is rated with power (P) and voltage (V) which is known as its power rating. For example: If an electric bulb is rated as 50W-220V, it means that when the bulb is lighted on a 220 V supply, it consumes 50 W electrical power.
(a) To calculate the resistance of the appliance, the expression is:
Resisteance , R = `"V"^2/"P"`
(b) The safe limit of current I is : I = `"P"/"V"`
संबंधित प्रश्न
Find the expression for the resistors connected in series and write the two characteristics of it. (Draw figure).
Write down an expression for the resistance of a metallic wire in terms of the resistivity.
What is the resistance between A and B in the figure given below?
State the order of resistivity of (i) a metal, (ii) a semiconductor and (iii) an insulator.
Name the material of wire used for making standard resistances. Give a reason.
How does the resistivity of an alloy such as constantace depends on temperature.
State a relation between electrical power, resistance and potential difference in an electrical circuit.
2Ω resistor A, 1Ω resistor B and 4Ω resistor C are connected in parallel. The combination is connected across a 2V battery of negligible resistance. Draw the diagram of the arrangement and calculate:
(i) The current in each resistor A and C,
(ii) The current through battery.
When a 4 Ω resistor is connected across the terminals of a 2 V battery, the number of coulombs passing through the resistor per second is:
