1.Two point charges, q =8×10

^{-8}C and Q= -2×10^{-8}C are separated by a distance of 10 cm in air. What is the net electric field at the mid- point between the charges.**Using the formulae=F/Q =3.6x 10**

^{5 }
2. Two point charges 4 Q, Q are separated by 1 m in air.
At what point on the line joining the charges is the electric field intensity
zero? Q9

**x=2/3 m**

3 .Two point charges of 16μC
and -9μC are placed 8cm apart in air. Determine the position of the point at
which resultant electric field is zero.

4 .Eight identical point
charges of q Coulomb each are placed at corners of a cube of each side 0.1m
.Calculate electric field at the center of the cube. Calculate the field at the
center when one of the corner charges is removed.

**i) zero ii) E = (1.2 x 10**

^{12})q N/C
5. What are the magnitude and
direction of electric field at the center of the square in fig if q=1.0 x 10 -8C and a = 5cm?

6. A charge of 4 x 10 -9 C is
distributed uniformly over the circumference of a conducting ring of radius
0.3m. Calculate the field intensity at a point on the axis of the ring at 0.4m
from its centre, also at the center.

**At the center of ring, r = 0,**

**So E = 0**

7. Charge q1=+6.0nC is on y
axis at y=+3 cm and charge q2 = -6nCis on y axis at y=-3cm .Calculate force on
test charge q0= 2 nC placed on x axis at x=4cm.

**-51.8 j μN**

8.ABC is an equilateral
triangle of each side 5 cm. two charges of ±50/3 x 10-3 μC are placed
at A and B respectively. Calculate magnitude and direction of resultant
intensity at C.

**6 x 10**

^{4}N/C parallel to AB from + charge to – charge.