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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
The substance having infinitely high electrical resistance is called:
(a) conductor
(b) resistor
(c) superconductor
(d) insulator
Name the material which is the best conductor of electricity.
State the order of resistivity of (i) a metal, (ii) a semiconductor and (iii) an insulator.
Name a substance of which the resistance remains almost unchanged by the increase in temperature.
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.
Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be ______.
State expression for Resistance connected in series.
Two resistors having 2Ω and 3Ω resistance are connected—(i) in series, and (ii) in parallel. Find the equivalent resistance in each case.
What is the maximum resistance which can be made using five resistors each of `1/5` W?
