Forces between charged and uncharged objects

3 marks · Normal

Describe an experiment to show that there are forces of attraction and repulsion between charged rods. In your answer, name the main items used and outline how you would observe both attraction and repulsion.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

Suspend a light rod (e.g. plastic) using thread. Charge it (e.g. by rubbing with a cloth). Bring another charged rod close: if the rods have the same charge, the suspended rod moves away (repulsion); if the opposite charge, it moves towards (attraction).

Must show: Description of both attraction and repulsion setups, Named items (e.g. plastic rods, cloth, thread)

Common mistakes: Failing to describe both attraction and repulsion

Show mark scheme and worked solution

Marking points

B1 · 1 mark · Names suitable items (e.g. plastic rods, woolen cloth, thread)

B2 · 1 mark · Describes method for observing repulsion (like charges)

B3 · 1 mark · Describes method for observing attraction (unlike charges)

Worked solution

Hang a light plastic rod using a thread so that it can swing freely. Charge the suspended rod by rubbing it with a cloth. Bring another rod, also charged, close to it. If both rods are charged the same way, the suspended rod moves away (shows repulsion). If the second rod is charged oppositely, the suspended rod moves towards it (shows attraction).