MEDIUM
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In Circuit-1 and Circuit-2 shown in the figures, R1=1Ω,R2=2Ω and R3=3Ω.
P1 and P2 are the power dissipations in Circuit-1 and Circuit-2 when the switches S1 and S2 are in open conditions, respectively.
Q1 and Q2 are the power dissipations in Circuit-1 and Circuit-2 when the switches S1 and S2 are in closed conditions, respectively.

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Which of the following statement(s) is(are) correct?

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Important Questions on Current Electricity

MEDIUM
In a building there are 15 bulbs of 45W , 15 bulbs of 100W,15 small fans of 10W and 2 heaters of 1kW . The voltage of electric main supply is 220V . The minimum fuse capacity (rated value) of the building will be:
MEDIUM
A current of 2mA was passed through an unknown resistor which dissipated a power of 4.4 W. Dissipated power when an ideal power supply of 11V is connected across it is:
MEDIUM
The resistive network shown below is connected to a D.C. source of 16 V. The power consumed by the network is 4 W. The value of R is:
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EASY
An inverter battery operated on 24 V and has negligible internal resistance. It is rated at 140 ampere-hour. What external resistance would have to be connected to the battery, if it were to be discharged in 14 hours.
MEDIUM
Two electric bulbs, rated at 25 W, 220 V  and 100 W, 220 V, are connected in series across a 220 V voltage source. If the 25 W and 100 W bulbs draw powers P1 and P2 respectively, then:
HARD
A student in a town in India, where the price per unit (1 unit =1kWh ) of electricity is  5.00, purchases a 1kVA UPS (uninterrupted power supply) battery. A day before the exam, 10 friends arrive to the student's home with their laptops and all connect their laptops to the UPS. Assume that each laptop has a constant power requirement of 90 W. Consider the following statements.
I. All the 10 laptops can be powered by the UPS, if connected directly.
II. All the 10 laptops can be powered, if connected using an extension box with a 3 A fuse.
III. If all the 10 friends use the laptop for 5 h, then the cost of the consumed electricity is about  22.50 .
Select the correct option with the true statements.
MEDIUM
A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when:
EASY
An electric bulb rated as 200 W at 100 V is used in a circuit having 200 V supply. The resistance R that must be put in series with the bulb so that the bulb delivers the same power is ______ Ω.
HARD

A light bulb of resistance R=16 Ω is attached in series with an infinite resistor network with identical resistances as shown below. A 10 V battery derives a current in the circuit. What should be the value of r such that the bulb dissipates about 1 W of power?

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MEDIUM

A uniform metallic wire of length L is mounted in two configurations. In configuration 1 (triangle), it is an equilateral triangle and a voltage, V is applied to corners A and B. In configuration 2 (circle), it is bent in the form of a circle, and the potential V is applied at diametrically opposite points P and Q. The ratio of the power dissipated is configuration 1 to configuration 2 is.

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EASY
Two identical cells are first connected in series and then in parallel. The ratio of power consumed by them is
MEDIUM
A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance, R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is
EASY
Two electric bulbs rated P1 watt, V volts and P2 watt, V volts are connected in parallel and V volts are applied to it. The total power will be :-
MEDIUM

Consider the following two circuits

A : 20 bulbs are connected in series to a power supply line

B : 20 bulbs identical to A are connected in a parallel circuit to an identical power supply line

Identify which of the following is not true

MEDIUM

A zener diode having zener voltage 8 V and power dissipation rating of 0.5 W is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance Rp is _____Ω.

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MEDIUM
An electric bulb of 500 W at 100 V is used in a circuit having a 200 V supply. Calculate the resistance R to be connected in series with the bulb so that the power delivered by the bulb is 500 W.
MEDIUM
What will be the maximum number of 60 W bulbs in parallel that can be turned on when a house wiring supplied with a 220 V supply line is protected by a 6 ampere fuse?
EASY
In which of the following devices, the eddy current effect is not used?
EASY
If the current through a resistor in a circuit increases by 3%, the power dissipated by the resistor
HARD
The supply voltage to a room is 120 V. The resistance of the lead wires is 6  Ω . A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?