A thin, uniform, hollow metal sphere of radius R R\,R has a mass M M\,M and carries a net negative charge −Q-Q−Q. It is isolated in space and produces both a gravitational field and an electric field in its surrounding region. Which statement is not correct?
At any point where r>Rr > Rr>R, both the gravitational field and the electric field point radially inwards towards the centre of the sphere.
At any point where r<Rr < Rr<R inside the hollow cavity, both the gravitational field strength and the electric field strength are zero.
At any point where r<Rr < Rr<R inside the hollow cavity, both the gravitational potential and the electric potential are zero.
For r>Rr > Rr>R, both the gravitational field strength and the electric field strength are inversely proportional to the square of the distance from the centre.
15 exam-style questions on OCR A A Level Physics Electric fields, covering Point and spherical charges, Coulomb's law, Uniform electric field, and Electric potential and energy. Each one has a worked solution and a mark scheme showing where the marks go.