Q. 575.0( 2 Votes )

# Consider the situation of the previous problem. A charge of –2.0 × 10^{–4} C is moved from the point A to the point B. Find the change in electrical potential energy U_{B} – U_{A} for the cases (a), (b) and (c).

Answer :

**Given:**Magnitude of Electric field: E = 20 N C

^{–1}

Magnitude of charge moved from A to B = –2.0 × 10

^{–4}C

**Formula used:**

Change in Electrical potential energy is

Here, ΔU is change in Electrical potential energy, Δ V is change in potential and q is the charge displaced.

ΔU = U

_{B}-U

_{A}where U

_{B}is electric potential energy at B and U

_{A}is electric potential energy at A

(a)

A = (0, 0); B = (4m, 2m)

∴ V

_{B}-V

_{A}= -20×(4-0) = -80 V

Thus Change in Electrical potential energy is

U

_{B}-U

_{A}= (V

_{B}– V

_{A})× q

∴ Δ U = -80 × -2.0× 10

^{-4}

∴ Δ U = 0.016 J

(b)

A = (4m, 2m); B = (6m, 5m)

∴ V

_{B}-V

_{A}= -20×(6-4) = -40 V

Thus Change in Electrical potential energy is

U

_{B}-U

_{A}= (V

_{B}– V

_{A})× q

∴ Δ U = -40 × -2.0× 10

^{-4}

∴ Δ U = 0.008 J

(c)

A = (0, 0); B = (6m, 5m)

∴ V

_{B}-V

_{A}= -20×(6-0) = -120 V

Thus Change in Electrical potential energy is

U

_{B}-U

_{A}= (V

_{B}– V

_{A})× q

∴ Δ U = -120 × -2.0× 10

^{-4}

∴ Δ U = 0.024

Hence, for the cases (a),(b) and (c) the change in electric potential energy when the charge is moved from A to B is 0.016 J,0.008 J , 0.024 J respectively.

Rate this question :

Which of the following quantities do not depend on the choice of zero potential or zero potential energy?

HC Verma - Concepts of Physics Part 2Consider the situation of the previous problem. A charge of –2.0 × 10^{–4} C is moved from the point A to the point B. Find the change in electrical potential energy U_{B} – U_{A} for the cases (a), (b) and (c).

A point charge q is rotated along a circle in the electric field generated by another point charge Q. The work done by the electric field on the rotating charge in one complete revolution is

HC Verma - Concepts of Physics Part 2Two identical particles, each having a charge of 2.0 × 10^{–4} C and mass of 10g, are kept at a separation of 10 cm and then released. What would be the speeds of the particles when the separation becomes large?

The kinetic energy of a charged particle decreases by 10 J as it moves from a point at potential 100V to a point at potential 200V. Find the charge on the particle.

HC Verma - Concepts of Physics Part 2How much work has to be done in assembling three charged particles at the vertices of an equilateral triangle as shown in figure?

Two charged particles, having equal charges of 2.0 × 10^{–5} C each, are brought from infinity to within a separation of 10 cm. Find the increase in the electric potential energy during the process.

When the separation between two charges is increased, the electric potential energy of the charges

HC Verma - Concepts of Physics Part 2