Capacitors and Unit of Capacitance

Q. A: The potential difference between two concentric spherical shells depends only on the charge ofinner shell. R: The electric field in the region in between two shells depends on the charge of inner shel and electric field is the negative of potential gradient.

Q.

A 600 pF capacitor is charged by a 200 V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?

Q.

The plates of a parallel plate capacitor have an area of 90 cm² each and are separated by 2.5 mm. The capacitor is charged by connecting it to a 400 V supply.

(a) How much electrostatic energy is stored by the capacitor?

(b) View this energy as stored in the electrostatic field between the plates, and obtain the energy per unit volume u. Hence arrive at a relation between u and the magnitude of electric field E between the plates.

Q.

Why is capacitor called condenser ?

Q.

What is the advantage of a capacitor?

Q.

Show that the force on each plate of a parallel plate capacitor has a magnitude equal to (½) QE, where Q is the charge on the capacitor, and E is the magnitude of electric field between the plates. Explain the origin of the factor ½.

Q.

Can Capacitors store AC voltage?

Q.

A 12 pF capacitor is connected to a 50V battery. How much electrostatic energy is stored in the capacitor?

Q. Capacitance does not depend on the charge and the potential on the surface of the conductor.

1. True
2. False

Q.

How much charge is stored in a capacitor?

Q. Capacitance of a capacitor is the measure of its ability to .

1. resist flow of current
2. store charge
3. allow flow of current

Q. A hollow uncharged spherical conductor has inner radius A and outer radius b. A positive point charge +q is in the cavity at the center of the sphere (Fig. 3.48). Find the potential V( r) everywhere, assuming that at V=0 at r= infinty

Q.

In the system shown middle plate is having a charge $+Q$, the other plates are charge neutral initially and both the switches are open. If we close both the switches simultaneously find out the final charge on the inner side of the left most plate.

1. $\frac{-Q{d}_1}{d_1+d_2}$
2. $\frac{-Q}{2}$
3. $\frac{-Q{d}_2}{d_1+d_2}$
4. zero

Q. 10. Two electric dipoles are placed parallel to eachother as shown in figure. The potential at a pointP (at equitorial position of dipoles) is90+2qi 90+3q-3qK(2q)2) , 2-2+ r1 2K(3q)(4) Zero

Q. Capacitance of Earth is very large compared to 1 farad.

1. False
2. True

Q. Potential difference between points A and B and the Periphery of a spherical cavity of radius R is made in a solid non conducting sphere of uniform charge density rho is

Q. ntA: The potential difference between two concentric spherical shells depends only on the charge of the inner shelln ntR: The electric field in the region between the two shells depends on the charge of the inner shell and electric field is negative of potential gradientn

Q. On what factors does the capacitance of a parallel plate capacitors depend $?$

1. Area of the plates
2. Potential difference across the plates
3. Both $a$ and $b$ are correct
4. Charge on the plates

Q.

What are the two applications of capacitors?

Q. What is the uses of a capacitor?

Q. what are uses of capacitors ?

Q. When a dielectric slab is gradually inserted between the plates of an isolated parallel-plate capacitor, the energy of the system decreases. What can you conclude about the force on the slab exerted by the electric field?

Q. In the given circuit, separation between plates of capacitor is doubled very slowly, keeping battery connected. While increasing seperation between plates, .

1. Work done by battery will be positive
2. Heat will be generated in resistance
3. Work done by battery will be negative.
4. Work done by electrostatic force will be positive

Q.

Where do we use an inductor and capacitor? What are their applications?

Q. 28.a parallel plate capacitor of plate area A and plate separation d is charged to a potential V are disconnected.A slab of dielectric constant K is the inserted between the plates.The work done on the system during the process of inserting the slab

Q. Capacitance of a capacitor is the measure of its ability to .

1. resist flow of current
2. store charge
3. allow flow of current

Q.

what is the purpose of obtaining a high value of time constant in rc filters?

Q.

Select the correct statement(s)

1. Capacitance of a capacitor depends on the charge on it

2. Capacitance of a capacitor does not depend on the charge on it

3. Capacitance of a capacitor does not depend on the potential difference

4. Capacitance of a capacitor does not depend on the material with which the capacitor is prepared

Q. Two small identical parallel plate capacitors are arranged along a line. The sepration r between the capacitors is much larger than the separation between plates l of each capacitor (r very greater than l ). The capacitors are charged to q1 and q2 respectively.Then find force between capacitors and electric field produced by first capacitor over other?

Q. Why do we need capacitor to store energy when we already have battery to do that?

1. Because batteries are obsolete
2. Because capacitor can store a very-very large amount of energy
3. Because a capacitor can provide the stored energy back relatively slowly
4. Because a capacitor can provide the stored energy back relatively quickly.