NCERT Physics Class12 Exampler Chapter-2 Electrostatic Potential and Capacitance Part-4

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Q.13 A parallel plate capacitor is connected to a battery as shown in figure. Consider two situations:

R: Key K ¡s kept closed and plates of capacitors are moved apart using Insulating handle.

S: Key K is opened and plates of capacitors are moved apart using insulating handle.

Choose the correct option(s).

Image of Capacitor Plate

Image of Capacitor Plate

Image of Capacitor Plate

  1. In R: Q remains same but C changes.

  2. In S: V remains same but C changes.

  3. In R: V remains same and hence Q changes.

  4. In S: Q remains same and hence V changes.

Answer: C and D

Very Short Answer

Q.14 Consider two conducting spheres of radii and with . lf the two are at the same potential, the larger sphere has more charge than the smaller sphere. State whether the charge density of the smaller sphere is more or less than that of the larger one.

Answer: More

Solution: Since, the two spheres are at the same potential, therefore

Or

As , this imply that .

The charge density of the smaller sphere is more than that of the larger one.

Q.15 do free electrons travel to region of higher potential or lower potential?

Answer: Higher Potential

Solution:

The force on a charge particle in electric field

The free electrons (negative charge) experience electrostatic force in a direction opposite to the direction of electric field.

The direction of electric field is always from higher potential to lower. Hence direction of travel of electrons is from lower potential to region of higher potential.

Q.16 can there be a potential difference between two adjacent conductors carrying the same charge?

Answer: Yes, if the sizes are different.

Solution:

We define capacitance of a conductor ¡s the chage of conductor and V is the potential of the conductor. For given charge potential . The capacity of conductor depends on its geometry, so two adjacent conductors carrying the same charge of different dimensions may have different potentials.