Page 30 - Electrostatics 11

Grade 11 © GC Shiba

☻ State and explain Gauss theorem and use it to find the electric field due to
a charged sphere at a point

a. Outside the sphere and

b. Inside the sphere
☻ What is electric flux? State and explain Gauss law in electrostatics. Use it to

find electric field intensity due to infinite plane sheet of charge.
☻ Define electric field intensity and dielectric constant of a medium. Also

derive a relation between the electric field with the potential gradient.

☻ What is the physical difference between electric potential and electric field
intensity? Derive an expression for the potential differences between two

points in the electrostatic field.

☻ Define electric potential. Derive an expression for the electric potential due
to a point charge at a distance r from it.

☻ State and explain Gauss law in electrostatics. Use it to find the electric field

intensity due to a line charge.
☻ State and explain Gauss theorem in electrostatics and use it to find the

electric field intensity due to a hollow charged spherical conductor.

☻ Define potential and electric field at a point in an electrostatic field. Derive
a relation between the electric potential and the electric field strength at a

point.

Numerical Problems (3 Marks)

1 Find the electric intensity at corner C of equilateral triangle of side 1 m if
-6
-6
2 × 10 C and -3 × 10 C are at corner of A and B of triangle.
4
4
Ans: 1.8 × 10 N/C along AC and 2.7 × 10 N/C along BC
2 Find electric potential at corner C of equilateral triangle of side 1 m if
-6
-6
2 × 10 C and -3 × 10 C are at corners A and B of a triangle.
Ans:

3 Two large parallel metal plates carry opposite charges. They are separated
by 10 cm and p.d. of 500 volts is applied on them.

a. What is the magnitude of electric field strength between them?
−9
b. Compute the work done by this field on a charge of 2 × 10 as it
moves from higher to the lower potential.

-6
Ans: 10 J
30 Electrostatics