What is the opposite of gravitational energy

Gravitational Potential Energy is dependent upon some mass (m) located at some height/distance (h) away from another mass which causes the first mass to experience a gravitational acceleration (g).

In other words, when two masses are separated by some distance both masses posses gravitational potential energy.

Electrical Potential is very similar to gravitational, but it deals with charges instead of mass.

When two (non neutral) electric charges are separated, the charges possess electric potential energy in that both charges feel an electric force acting upon them which causes acceleration. When these charges are held a given distance apart, they posses some potential energy.

Charged in and of themselves may also posses gravitational PE in that not only do they have an electric charge, but that also have mass (for example, electrons and Protons). In most cases, the gravitational PE is ignored since the electric force is so much greater than the gravitational force.

PE_g = mgh

in a uniform gravitational field.

PE_g = (G * M_1 * m_2) / r^2

Where G is the universal gravitational constant, m (and M) is the mass of the object, g is the gravitational acceleration, h is the distance the object is held above the gravitational field, and r is the radium between the two objects' centers of mass.

G = 6.67 E-11

PE_e = (k * Q_1 * q_2) / r^2

where k is Coulomb's constant (= 8.988 E9), Q and q are the charges on the two particles, and r is the distance between the centers of charge on the two particles.

EDIT:

Energy is of course measured in Joules.

Do not confuse "Electrical Potential" and "Electrical Potential Energy", although the terms are similar. Electrical Potential is just like any other energy, measured in Joules. Electrical Potential is measured in "Volts".

1 volt = 1 Joule / Coulomb

An electrical potential will cause an electric current, and electric current has a electrical power given the Electrical Potential * Current. Electrical current is given as the charge passing throug a given segment of wire per second, Coulomb / second.

Power = volts * amps