- CH.PHYSICS

# Important Questions in Electric Charges and Fields Lesson for CBSE +2 Students

**1)** Answer the following questions.

## a. Using Gauss law, derive an expression for the electric field intensity at any **point outside** a uniformly charged thin spherical shell of radius **R** and charge density **q/A** C/m2.

## b. Draw the field lines when the charge density of the sphere

## i. Positive,

## ii. Negative.

## c. A uniformly charged conducting sphere of 2.5 m in diameter has a surface charge density of 100 µC/m2.

## Calculate the (i) charge on the sphere (ii) total electric flux passing through the sphere.

**2) ** Using Gauss’s law, derive an expression for the **electric field intensity** at any point near a uniformly charged thin wire of linear charge density λ C/m.

**3) **Using Gauss’ law deduce the expression for the electric field due to a uniformly charged spherical conducting shell of radius R at a point

## **i)** Outside and ** ii)** Inside the shell.

## Plot a graph showing variation of electric field as a function of r >R and r < R.(r being the distance from the center of the shell.

**4)** Define electric flux. Write its S.I. units. Using Gauss’s law, prove that the electric field at a point due to a uniformly charged infinite plane sheet is independent of the distance from it. How is the field directed if ** i)** The sheet is positively charged, **ii)** Negatively charged?

**5)** Deduce the expression for the torque acting on a dipole of dipole moment **p **in the presence of a uniform electric field **E.**

**6) ** Two point charges +q and – 2q are placed at the vertices B and C of an equilateral triangle ABC of side *a *as shown in the figure. Obtain the expression for

## i. The magnitude and

## ii. The direction of the resultant electric field at the vertex A due to these two charges.

## __ONE MARK QUESTIONS__

__ONE MARK QUESTIONS__