What the Simulation Shows
The Gold Leaf Electroscope simulation shows a realistic instrument — a metal disc at the top, connected by a metal stem down into a glass jar, with two gold leaves hanging from the bottom of the stem inside the jar. Six buttons let students interact with it in sequence.
Touch with + Rod adds positive charge to the disc by conduction — electrons transfer from the scope to the rod, leaving both leaves positively charged. They repel and swing apart. Pressing repeatedly increases the charge and widens the angle up to 40°.
Touch with − Rod does the opposite — electrons transfer from the rod onto the scope, both leaves become negative, and they diverge by the same principle.
Bring + Rod Near (Induction) holds a charged rod close without touching. A glowing animated rod appears near the disc. Free electrons inside the scope are attracted upward toward the positive rod, making the disc top negative and the leaves positive — the leaves still diverge, but no charge has been transferred yet. The disc correctly shows a − symbol.
Bring − Rod Near pushes electrons down into the leaves — disc top becomes positive, leaves become negative — and they still diverge, because both carry the same sign.
Earth / Ground connects the scope to earth. If already charged, the charge drains away and the leaves close. If used during induction, electrons flow to or from earth to neutralise the leaves — and when the rod is removed, the scope is left with a permanent induced charge of the opposite sign to the rod.
Reset returns everything to neutral instantly.
The info panel on the right explains in plain English exactly what is physically happening at each step — which way electrons are moving and why the leaves respond as they do.
Suggested Class Activity
Topic: Charging by conduction, induction, and earthing Level: GCSE Physics Year 10/11 Duration: 20 minutes · Pairs
Starter (3 min): Ask — “If I touch a charged balloon to the top of this instrument, what do you think will happen to the leaves?” Take two answers, then load the simulation.
Guided tasks (12 min):
- Press Touch with + Rod three times. Sketch the leaves. Note the angle. What charge do the leaves carry and why do they repel?
- Press Touch with − Rod three times on a reset scope. Does the angle differ? Why do the leaves still diverge even though the charge is opposite?
- Press Bring + Rod Near. Leaves diverge — but is any charge on the scope yet? Then press Earth / Ground while the rod is still near. What happens to the leaves? Now reset — what charge does the scope hold?
- Repeat step 3 with the negative rod. Compare the final charge each time.
Key question for discussion: The rod never touches the scope in steps 3 and 4 — so how does the scope end up permanently charged?
Plenary (5 min): Students use the words electrons, conduction, induction, repulsion, earthing to write two sentences explaining the difference between charging by contact and charging by induction.
Real-world link: Lightning conductors work by induction — the charged cloud induces an opposite charge at the tip of the rod, which then discharges safely to earth before a strike occurs.