10 question-answer on electric flux
1. A cylinder of radius R and length l is placed in a uniform electric field E parallel to the axis of the cylinder. The total flux over the curved surface of the cylinder is:
(a) Zero
(b) πR2E
(c) 2 πR2E
(d) E/ πR2
Ans: (a)
2. Electric flux at a point in an electric field is:
(a) Positive
(b) Negative
(c) Zero
(d) None of these
Ans: (c)
3. Electric flux over a surface in an electric field may be
(a) Positive
(b) Negative
(c) Zero
(d) Positive, negative, zero
Ans: (d)
4. If a unit charge is taken from one point to another over an equipotential surface, then
(a) Work is done on the charge
(b) Work done by the charge
(c) Work on the charge is constant
(d) No work is done
Ans: (d)
5. Charges present outside a close surface do not contribute to electric flux
(a) True
(b) False
Ans: (a)
6. Positive electric flux indicates that electric lines of force are directed
(a) Outwards
(b) Inwards
(c) Outwards or inwards
(d) None of these
Ans: (a)
7. Negative electric flux indicates that electric lines of force are directed
(a) Outwards
(b) Inwards
(c) Outwards or inwards
(d) None of these
Ans: ( b)
8. Which of the following is discontinuous across a charged conducting surface
(a) Electric potential
(b) Electric intensity
(c) Both electric potential and intensity
(d) None of the above
Ans: (b)
9. Electric field intensity at a point due to an infinite sheet of charge having surface charge density ∂ is E. if sheet were conducting electric intensity would be:
(a) E/2
(b) E
(c) 2E
(d) 4E
Ans: ( c)
10. A surface encloses and electric dipole. The flux through the surface is:
(a) Zero
(b) Positive
(c) Negative
(d) Infinite
Ans: ( a)