# NCERT Physics Class 12 Exemplar Chapter 1 Electric Charges and Fields Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

Get top class preparation for CBSE/Class-12 Accountancy right from your home: fully solved questions with step-by-step explanation- practice your way to success.

Q. 18 Sketch the electric field lines for a uniformly charged hollow cylinder shown in Fig. Tittle: The Uniformly Charged Hollow Cylinder

Solution:

The electric field lines start from positive charges and move towards infinity and meet plane surface normally as shown in the figure below: Tittle: The Meet Plane Surface Normally

Q. 19 What will be the total flux through the faces of the cube (Fig.) with side of length if a charge is placed at Flux through Face

(a) A: a corner of the cube.

(b) B: mid-point of an edge of the cube.

(c) C: centre of a face of the cube.

(d) D: mid-point of B and C.

Solution:

(a) Use of symmetry consideration may be useful in problems of flux calculation. We can imagine the charged particle is placed at the centre of a cube of side . We can observe that the charge is being shared equally by cubes. Therefore, total flux through the faces of the given cube . Tittle: The Corner of the Cube

(b) If the charge is placed at . middle point of an edge of the cube, it is being shared equally by cubes. Therefore, total flux through the faces of the given cube . Charge at Middle Point B

(c) If the charge is placed at . the centre of a face of the cube, it is being shared equally by cubes. Therefore, total flux through the faces of the given cube Charge at Point C

(d) Finally, if charge is placed at . the mid-point of and , it is being shared equally by cubes. Therefore, total flux through the faces of the given cube . Charge at Point D