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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
Choose the correct alternative and rewrite the following sentence.
When the resistance of a conductor increases, the current will ________ increase.
A battery and three lamps are connected as shown:
Which of the following statements about the currents at X, Y and Z is correct?
(a) The current at Z is greater than that at Y.
(b) The current at Y is greater than that at Z.
(c) The current at X equals the current at Y.
(d) The current at X equals the current at Z.
V1, V2 and V3 are the p.ds. across the 1Ω, 2Ω and 3Ω resistors in the following diagram, and the current is 5 A.
Which one of the columns (a) to (d) shows the correct values of V1, V2 and V3measured in volts?
`V_1` `V_2` `V_3`
(a) 1.0 2.0 3.0
(b) 5.0 10.0 15.0
(c) 5.0 2.5 1.6
(d) 4.0 4.0 2.0
For a heater rated at 4 kW and 220 V, calculate:
(a) the current,
(b) the resistance of the heater,
(c) the energy consumed in 2 hours, and
(d) the cost if 1 kWh is priced at Rs 4.60.
A current of 0.3 A is flowing through a branch of 6 Ω resistors in a junction as shown in fig. . Calculate the
(a) P.d. across the junction XY,
(b) Current flowing through 9Ω and 24Ω
( c) P.d. across 24 Ω resistor, and
( d) e.m.f. of the cell.
60 joules of heat was dissipated in a resistor when 20 C flowed for 5 s. Calculate:
(a) P.d. across the resistor,
(b) Resistance of the resistor, and
(c) Average power dissipated in the resistor.
What is the SI unit for the current?
What is the rate at which charges flow past a point on a circuit?
