Electric potential
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Define electric potential at a point.
Electric potential at a point is the work done per unit positive charge in bringing a small test charge from infinity to that point. It is a scalar quantity, measured in volts (V).
What is the relationship between electric field strength and electric potential gradient?
The electric field at a point is equal to the negative of the potential gradient at that point. Mathematically, E = -dV/dr, where E is electric field strength and dV/dr is the potential gradient.
State the formula for the electric potential due to a point charge Q at a distance r.
The electric potential (V) is given by V = Q / (4πε₀r), where Q is the charge, r is the distance from the charge, and ε₀ is the permittivity of free space.
Explain how the concept of electric potential leads to electric potential energy.
Electric potential defines the potential energy per unit charge at a location. Multiplying the electric potential (V) at a point by the charge (q) placed at that point gives the electric potential energy (EP): EP = qV.
State the formula for the electric potential energy of two point charges, Q and q, separated by a distance r.
The electric potential energy (EP) is given by EP = Qq / (4πε₀r), where Q and q are the charges, r is the distance between them, and ε₀ is the permittivity of free space.
Describe the sign convention for electric potential energy.
If the charges are of the same sign (both positive or both negative), the electric potential energy is positive, representing repulsive forces. If the charges are of opposite signs, the electric potential energy is negative, representing attractive forces.
How does electric potential change as you move closer to a positive charge?
Electric potential increases as you move closer to a positive charge. This is because work must be done by an external force to bring a positive test charge closer to another positive charge against the repulsive electric field.
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