Advertisements
Advertisements
Question
The electrostatic potential is given as a function of x in figure (a) and (b). Calculate the corresponding electric fields in regions A, B, C and D. Plot the electric field as a function of x for figure (b).
Advertisements
Solution
Figure a:
`vec"E" = - "dv"/"dx" hat"i"`
From 0 to 0.2 m,
`"E"_"x" = "dv"/"dx" = 3/0.2 = 30/2 = 15`Vm-1 (region A)
`"E"_"x" = "dv"/"dx"` = 0
Since the potential is constant (region B)
`"E"_"x" = "dv"/"dx" = (-2)/0.2 = (-20)/2` = - 10 Vm-1 (region c)
`"E"_"x" = "dv"/"dx" = 6/0.2 = 60/2` = 30 Vm-1 (region d)
Figure b:

`"E"_"x" = "dv"/"dx"` = - 30 Vm-1 (region 0-1 cm)
`"E"_"x" = "dv"/"dx"` = 30 Vm-1 (region 1-2 cm)
`"E"_"x" = "dv"/"dx"` = 0 (region 2-3 cm)
`"E"_"x" = "dv"/"dx"` = 30 Vm-1 (region 3-4 cm)
`"E"_"x" = "dv"/"dx"` = - 30 Vm-1 (region 4-5 cm)
APPEARS IN
RELATED QUESTIONS
Which charge configuration produces a uniform electric field?
Rank the electrostatic potential energies for the given system of charges in increasing order.

A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface. The correct plot for electrostatic potential due to this spherical shell is
Give the relation between electric field and electric potential.
Define ‘electrostatic potential energy’.
Derive an expression for electrostatic potential due to a point charge.
Obtain an expression for potential energy due to a collection of three point charges which are separated by finite distances.
Derive an expression for electrostatic potential energy of the dipole in a uniform electric field.
Five identical charges Q are placed equidistant on a semicircle as shown in the figure. Another point charge q is kept at the center of the circle of radius R. Calculate the electrostatic force experienced by the charge q.

Suppose a charge +q on Earth’s surface and another +q charge is placed on the surface of the Moon,
- Calculate the value of q required to balance the gravitational attraction between Earth and Moon
- Suppose the distance between the Moon and Earth is halved, would the charge q change?
(Take mE = 5.9 x 1024 kg, mM = 7.348 x 1022 kg)


