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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 resistors connected in series.
If five resistances, each of value 0.2 ohm, are connected in series, what will be the resultant resistance?
Three resistors of 6.0 Ω, 2.0 Ω and 4.0 Ω are joined to an ammeter A and a cell of emf 6.0 V as shown in the following figure. Calculate :
- the effective resistance of the circuit.
- the reading of ammeter.
To increase the effective resistance in a circuit, the resistors are connected in _______________ .
Name the material of wire used for making standard resistances. Give a reason.
State expression for Resistance connected in parallel.
A metal wire of resistance 6 Ω is stretched so that its length is increased to twice its original length. Calculate its new resistance.
Two wires of the same length and area made of two materials of resistivity ρ1 and ρ2 are connected in series to a source of potential V. The equivalent resistivity for the same area is:
Consider the following combinations of resistors:
The combinations having equivalent resistance 1 Q is/are ______.
