To separate the charges on two neutral conducting spheres so that one sphere has a net negative charge and the other has a net positive charge, the student can follow these steps:
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Bring a Charged Object Near the Spheres: The student should take a positively charged object (like a glass rod rubbed with silk) and bring it close to one of the neutral conducting spheres without touching it.
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Induce Charging: The presence of the positively charged object will cause the electrons in the neutral conducting sphere to be attracted towards the charged object. This will create a separation of charge in the sphere:
- The side of the sphere closest to the positive object will become negatively charged (due to the accumulation of electrons).
- The side of the sphere farthest from the positive object will be left with a positive charge (due to a deficiency of electrons).
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Grounding the Sphere with Negative Charge: At this point, while the positively charged object is still near, the student should connect the negatively charged sphere to the ground with a conducting wire. This allows excess electrons to flow from the sphere to the ground. When the wire is removed, the sphere will maintain a net positive charge, as it lost some electrons.
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Remove the Positive Object: After grounding the sphere and before removing the positively charged object, the student should first take away the ground connection. Now, the sphere that was near the positive object will have a net positive charge.
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Repeat for the Other Sphere: The student can repeat the process for the other conducting sphere by bringing it close to the positively charged object after grounding it. This time, electrons will be drawn from the ground into the sphere, leaving it with a net negative charge after disconnecting the ground.
Following these steps correctly, the student will end up with one sphere that is negatively charged and the other positively charged.