Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

(a)[1]

Define the term electric field strength.

(b)

As shown in Fig. 6.1, two parallel metal plates in a vacuum are separated by a distance of $15\,\text{mm}$. Applying a potential difference across them produces a uniform electric field between the plates. A particle of mass $1.7 \times 10^{-27}\,\text{kg}$ and charge $+1.6 \times 10^{-19}\,\text{C}$ is initially at rest at point A on one plate. The electric field moves the particle to point B on the other plate. At point B, the particle has kinetic energy $2.4 \times 10^{-16}\,\text{J}$.

(b(i))[2]

Calculate the particle's speed at point B.

(b(ii))[1]

State the amount of work done by the electric field in moving the particle from A to B.

(b(iii))[2]

Use your answer to part (ii) to find the force on the particle.

(b(iv))[3]

Determine the potential difference across the plates.

(b(v))[1]

On Fig. 6.2, sketch a graph to show how the kinetic energy of the particle changes with the distance $x$ from point A along the line AB. Numerical values for the kinetic energy are not required.

(iii)[2]

Use your answer to (ii) to determine the force on the particle.

(iv)[3]

Determine the potential difference across the plates.

(v)[1]

On Fig. 6.2, sketch a graph to show how the particle's kinetic energy varies with the distance $x$ measured from point A along AB. Numerical values for the kinetic energy are not required.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: force acting on unit positive charge in an electric field

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI