EASY
Earn 100

Give examples of bad solid conductors and liquid conductors.

Important Questions on Electricity and Circuits

MEDIUM
Two capacitors C1 and C2 are charged to 120 V and 200 V respectively. It is found that by connecting them together the potential on each one can be made zero. Then:
EASY
A parallel plate capacitor with plates of area 1 m2 each, are at a separation of 0.1 m. If the electric field between the plates is 100 N C-1, the magnitude of charge on each plate is: (Takeε0=8.85×1012 C2 N-1 m-2)
EASY
The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure:
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What is the value of current at t=4 s?
EASY
Two identical conducting spheres A and B carry an equal charges. They are separated by a distance much larger than their diameters, and the force between them is F. A third identical conducting sphere, C, is uncharged. Sphere C is first touched to A, then to B, and then removed. As a result, the force between A and B would be equal to:
HARD

Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is 220 V?

HARD
A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
EASY
A parallel plate capacitor is of area 6 cm2 and a separation 3 mm. The gap is filled with three dielectric materials of equal thickness (see figure) with dielectric constant K1=10, K2=12 and K3=14. The dielectric constant of a material which when fully inserted in above capacitor, gives same capacitance would be:

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MEDIUM
A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system
HARD

Calculate the effective resistance across AB.

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EASY

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The diagram above shows a circuit with the key k open. Calculate the resistance of the circuit when the key k is open and calculate the current drawn from the cell when the key k is open.

HARD
In the circuit shown in the figure, there are two parallel plate capacitors each of capacitance C. The switch S1 is pressed first to fully charge the capacitor C1 and the released. The switch S2 is then pressed to charge the capacitor C2. After some time, S2 is released and then is S3 pressed. After some time,
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MEDIUM
What are conductors? Give two examples.
HARD

Two identical parallel plate capacitors of capacitance each are connected in series with a battery of emf, E as shown. If one of the capacitors is now filled with a dielectric of dielectric constant k, the amount of charge which will flow through the battery is (neglect internal resistance of the battery)

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EASY

In the figure is shown a system of four capacitors connected across a 10 V battery. The charge that will flow from switch S when it is closed is:
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MEDIUM

An electron enters a parallel plate capacitor with horizontal speed μ and is found to deflect by angle θ on leaving the capacitor as shown. It is found that tanθ=0.4 and gravity is negligible.

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If the initial horizontal speed is doubled, then tanθ will be:

HARD

A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm and with a dielectric of dielectric constant 2.2 between them. When the electric field in the dielectric is 3 × 1 0 4  V/m , the charge density of the positive plate will be close to :

HARD

What are the charges stored in the 1 μF and 2 μF capacitors in the circuit below, once the currents become steady?

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HARD

A capacitor of μF is charged as shown in the diagram. When the switch S is turned to position 2, the percentage of its stored energy dissipated is

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EASY

What is a conductor of electricity? Give two examples.

EASY
Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason.