Buds Public School, Dubai
NAME: PHYSICS GRADE-12
Topic- Electric Charges and Fields
______
1. An electric dipole when held at 60 0 with respect to a uniform electric field of 104 N/C experienced a Torque of 9 x 10-26 Nm. Calculate dipole moment of the dipole?
2. A sphere of radius r1 encloses a change Q. If there is another concentric sphere S2 of radius r2 (r2 >r1) and there is no additional change between S1 and S2. Find the ratio of electric flux through S1 and S2?
3. Electric charge 5μC is uniformly distributed on the surface of a spherical balloon. Show
how electric intensity vary (a) on the surface (b) inside and (c) outside.
4.. Two point electric charges of value 3q and 5q are kept at a distance d apart from each other in air. A third charge Q is to be kept along the same line in such a way that the net force acting on 3q and 5q is zero. Calculate the position of charge Q in terms of‘d’.
5. A spherical Gaussian surface encloses a charge of 2μC
(i) Calculate the electric flux passing through the surface.
(ii) How would the flux change if the radius of the Gaussian surface is doubled and why?
8.what should be the position of charge q= 5μ C. for it to be equilibrium on the line joining two charges q1= - 4 μc and q1= - 4 μc separated by 9 cm .
9. Electric field components due to a charge inside a cube is Ex = a x, E Y and Ez= 0, Here a = 500N/C. Calculate the flux through the cube and the charge inside the cube.
0.1 m
0.1 m
10. A hollow cylindrical box of length 1m and area of cross-section 25cm2 is placed in a
three dimensional coordinate system as shown in the figure. The electric field in the region is given by E 50xi
Where E is in NC-1 and x is in meters. Find:
(i) Net flux through the cylinder.
(ii) Charge enclosed by the cylinder
11.