Question

What reference angle is chosen to simplify the potential energy formula for a dipole, and why?

Options

• θ₀ = 90° is chosen because cos 90° = 0, making the potential energy reference zero

• θ₀ = 180° is chosen because cos 180° = -1

• Any angle can be chosen as there is no preference

• θ₀ = 0° is chosen because cos 0° = 1

Answer 1

By setting the reference at θ₀ = 90° (dipole perpendicular to field), we get cos 90° = 0. This simplifies the potential energy expression to U(θ) = -pE cos θ, which has the dipole perpendicular to the field as the zero potential energy reference point.