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प्रश्न
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उत्तर
A switch is an on-off device for current in a circuit (or in an appliance). Its main function is either to connect or to disconnect an electrical appliance in an electric circuit.
Switches are always connected in the live wire of circuits so that when a switch is in 'off' position, no current flows through the appliance and its live and neutral wires are at same potential and it is safe to touch the live wire leading to the appliance, even when the fuse is blown.
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संबंधित प्रश्न
Write down the formula which relates electric charge, time and electric current
How many electrons are flowing per second past a point in a circuit in which there is a current of 5 amp?
In the circuit diagram given below, three resistors R1, R2, and R3 of 5 Ω, 10 Ω and 30 Ω, respectively are connected as shown
Calculate:
- current through each resistor.
- total current in the circuit.
- total resistance in the circuit.
Consider the circuit given below when A, B and C are three identical light bulbs of constant resistance. 
(a) List the bulbs in order of increasing brightness.
(b) If C burns out, what will be the brightness of A now compared with before?
(c) If B burns out instead, what will be the brightness of A and C compared with before?
An electric current flowing in a wire creates ______ around the wire.
A 720 W heater operates from a 220 V line voltage. Calculate:
(a) The electrical energy consumed by the heater in 3 h.
(b) The cost of electrical energy consumption at the rate of 60 paise per kWh.
Electrical power P is given by the expression P = (Q × V) ÷ time
(a) What do the symbols Q and V represent?
(b) Express the power P in terms of current and resistance explaining the meanings of symbols used there in.
Which of the following represents voltage?
