Question

student is designing an investigation of the distribution of charges in conductors. She will use two conducting spheres mounted on insulating stands in the investigation. The conducting spheres are shown.sphere.
She should place a positively charged rod near the left sphere.

She should place a negatively charged rod near the left sphere.
She should place a negatively charged rod near the left sphere.

She should place two negatively charged rods near each sphere.
She should place two negatively charged rods near each sphere.

She should place two positively charged rods near each sphere
should place a positively charged rod near the left sphere.
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Answer 1

I’m missing the diagram and the exact question wording, so I’m not sure which specific “choice” you need. Could you clarify what the student wants to investigate? For example:
- Do they want to demonstrate induction (redistribution of charge without contact)?
- Do they want to charge both spheres (by contact or by induction + grounding)?
- Do they want to show attraction/repulsion between charged objects?

Below are the typical setups and what each shows — pick the one that matches the investigation goal.

1) To demonstrate induction (charge redistribution on a single isolated conductor)
- Place a charged rod (either positive or negative) near the left sphere without touching it.
- Observation: free electrons in the sphere move so the near side acquires opposite sign and the far side acquires the same sign as the rod. The net charge on that isolated sphere stays the same.
- Use this to show that conductors redistribute charge in response to an external electric field.

2) To charge both spheres by conduction (contact)
- Give one sphere a net charge (e.g., touch it with a charged rod or connect it to a charged object).
- Then touch the two conducting spheres together (or connect them with a conducting wire) so charge flows until they share charge.
- Observation: both spheres end up with the same sign of charge; magnitude depends on sizes.

3) To charge the second sphere by induction (charging without contact)
- Bring a charged rod near the left sphere.
- Ground the right sphere (or touch it to earth) while the rod is still near the left sphere and the spheres are momentarily connected/close so charge can flow to ground or between them as intended.
- Remove the ground, then remove the rod.
- Observation: the spheres can end up with net charge opposite to the rod, depending on connections used.

4) To show attraction/repulsion between charges
- Charge left sphere positively (touch rod) and right sphere positively (same procedure), then bring them near each other to show repulsion.
- Or charge left positive and right negative to show attraction.

Notes on the options you listed:
- “Place a positively charged rod near the left sphere” — good for showing induction (same effect as using a negative rod, but the signs swap).
- “Place a negatively charged rod near the left sphere” — also fine for induction; results are sign-reversed compared to a positive rod.
- “Place two negatively charged rods near each sphere” or “two positively charged rods near each sphere” — unnecessary unless you specifically need both spheres charged (and using two rods just charges each sphere separately by contact).

If you tell me the specific learning outcome (e.g., “show induced separation of charge,” “charge two spheres and show repulsion,” or “show grounding during induction”), I’ll give a precise step-by-step procedure and the expected observations.