Electric Potential & Potential Energy — A/L Physics

What must I remember about Electric Potential & Potential Energy?

• Electric Potential (V): Work done by an external agent in bringing a unit positive test charge from infinity to that point without acceleration: V = W_ext / q0 = (1 / (4πε0)) * (Q / r) (scalar quantity, units Volt = J/C).
• Electric Potential Energy (U): Potential energy of a system of charges separated by distance r: U = (1 / (4πε0)) * (q1 q2 / r); U > 0 for like charges (repulsive, work required to bring together), U < 0 for opposite charges (attractive bound system).
• Potential Difference & Work Done: Work done in moving charge q between points A and B: W_AB = q (V_B - V_A) = q ΔV.
• Equipotential Surfaces: Loci of equal potential; E is everywhere orthogonal to equipotential surfaces (E = - dV/dr); Equipotential surfaces are closely spaced where electric field is strong and widely spaced where weak.

Test yourself (1 minute)

1. Electron-Volt (eV)

   Microscopic energy unit defined as the kinetic energy gained by an electron accelerating through a potential difference of 1 Volt: 1 eV = 1.602 × 10⁻¹⁹ J.

2. Zero potential reference

   Conventional zero potential is taken at infinity (V_∞ = 0) or Earth (Ground potential V_earth = 0).

Practise Electric Potential & Potential Energy questions today

Must know

• Potential of a Charged Conducting Sphere of radius R carrying charge Q: At external point (r ≥ R): V = Q / (4πε0 r); At surface (r = R): V_surface = Q / (4πε0 R); At ANY internal point (r < R): V_inside = V_surface = Q / (4πε0 R) (constant throughout cavity).

Source: NIE G.C.E. (A/L) Physics Resource Book - Unit 6: Electrostatic Field

What should I study first?

What comes next?

Next in the syllabus

Where does Electric Potential & Potential Energy fit in the syllabus?

Unit 6.3 · Year 1 · Term 3