# Which is the correct expression for work

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Which is the correct expression for work
done in moving a particle of charge q from a to b against an electric field , when the particle is not accelerated? a b q

Which of the equations given below are correct?
(a) All of them (b) 2, 3 & 4 (c) 1, 2 & 4 (d) 1, 3 & 4 (e) 2 & 4

(a) a (b) b (c) c (a) a (b) b (c) c
A negative charge -Q is placed on a conducting sphere. -Q c b a 1. At which of the points a, b, or c is the electrical potential the lowest? (a) a (b) b (c) c 2. At which of the points a, b, or c is the electrical potential the highest? (a) a (b) b (c) c

A positive charge +Q and a negative charge –q are separated by a distance d, and the potential VP = 0 at point P. This means that: P +Q -q d No force is acting on a test charge placed at point P. The electric field must be zero at point P. The net work in bringing Q to a distance d from q is zero. The net work needed to bring a charge from infinity to point P is zero.

4 1 2 3 Which two points shown in the diagram are at the same potential? 1 and 3 2 and 3 1 and 4 2 and 4 Which of the points shown in the diagram is at the highest potential? 1 2 3 4

The electric potential at a distance r from the center of a spherical charge of radius R and charge Q is given by the equation on the right. 1. The zero potential is taken at (a) the center of the sphere (b) the surface of the sphere (c) infinite distance from the sphere +Q r 2. A charge q is brought towards a spherical charge Q, as shown below. The direction of the potential energy of charge q is: (a) to the right b) to the left (c) neither: energy is a scalar

A positive q is moved to within a distance r1 from charge Q1 and r2 from charge Q2
The potential energy of q (relative to zero at infinity) is:

The potential difference between the cathode and the screen of a traditional TV is 12 kV.
What is the speed of an electron just before it hits the screen?

Three positive charges q1, q2, q3 are arranged as shown on the right, where Fi is the force on charge qi, and rij is the distance between charges i and j. The total potential energy of the system is (a) (b) (c) (d) Can't tell without knowing the angles.

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