In which case would electrical potential energy be built up and stored in the electric field?

a
A positive charge is moved toward a negative charge.
b
A positive charge is moved toward a positive charge.
c
A negative charge is moved away from a negative charge.
d
none of the above

You would have to PUSH a positive charge TOWARD another positive charge.

That means you would have to exert a force in the direction of motion - put positive work IN.
That INCREASES the potential energy stored. If you let go, they fly apart.

To determine in which case electrical potential energy is built up and stored in the electric field, we need to understand the concept of electric potential energy. Electric potential energy is the energy possessed by a charged particle due to its position in an electric field.

The formula for electric potential energy is given by:

PE = q * V

where PE is the electric potential energy, q is the charge of the particle, and V is the electric potential.

Now, let's examine each scenario mentioned:

a) A positive charge is moved toward a negative charge: In this scenario, both charges have opposite signs (positive and negative). When a positive charge is moved towards a negative charge, there is an attraction between the charges due to their opposite charges. The positive charge loses potential energy as it moves closer to the negative charge. This potential energy is transferred to the electric field and stored as electrical potential energy.

b) A positive charge is moved toward a positive charge: In this scenario, both charges have the same sign (positive). Since like charges repel each other, the positive charge will have to do work against the electric field to move towards the other positive charge. This work done is transformed into potential energy, which is transferred to the electric field and stored.

c) A negative charge is moved away from a negative charge: In this scenario, both charges have the same sign (negative). Similar to scenario b, like charges repel each other. Therefore, work is required to move the negative charge away from the other negative charge, resulting in potential energy being stored in the electric field.

d) None of the above: This option suggests that there is no scenario where electrical potential energy is built up and stored in the electric field. However, based on the explanations given above, cases a, b, and c all involve the buildup and storage of electrical potential energy.

Therefore, the correct answer is: none of the above (d).