Question

1. the following diagram represents a balloon and a wall. in diagram a, both the balloon and the wall are neutral. add +/- signs to show this. in diagram b, the balloon has been rubbed with rabbit fur, and taken on a charge. use +/- signs to represent the charge on the balloon (hint: use the electrostatic series) and show what happens to the wall.

Explanation:

Step 1: Understand the Initial State (Diagram a)

In the initial state (diagram a), both the balloon and the wall are neutral. A neutral object has an equal number of positive (protons) and negative (electrons) charges, so there is no net charge. So we represent both as having no +/ - signs.

Step 2: Analyze the Charging by Friction (Balloon)

When a balloon is rubbed with rabbit fur, electrons are transferred from the fur to the balloon. Electrons are negatively charged, so the balloon gains a net negative charge. This is the principle of charging by friction, where two objects are rubbed together, and electrons are transferred from one object to the other. So we mark the balloon with \(-\) signs to indicate its negative charge.

Step 3: Analyze Charge Induction (Wall)

The wall is a neutral conductor (or can be treated as one for static electricity purposes). When the negatively charged balloon is brought near the wall, the negative charges (electrons) in the wall are repelled (since like charges repel) and move to the far side of the wall. This leaves the side of the wall near the balloon with a net positive charge (because the positive charges (protons) in the wall are now unbalanced on the near - side). This is the principle of electrostatic induction, where a charged object induces a charge separation in a neutral conductor. So we mark the near - side of the wall with \(+\) signs.

Step 4: Analyze the Electrostatic Force

Since opposite charges attract, the negatively charged balloon and the positively charged (near - side of the) wall will experience an attractive electrostatic force. So in diagram b, we show the balloon being pulled towards the wall (drawing it closer to the wall) to represent this attractive force.

Answer:

Diagram a (Neutral State):

• Balloon: No +/ - signs (neutral, equal number of protons and electrons, so overall charge is zero).
• Wall: No +/ - signs (neutral, equal number of protons and electrons, so overall charge is zero).

Diagram b (After Rubbing and Interaction):

• Balloon: When a balloon is rubbed with rabbit fur, the balloon gains electrons (becomes negatively charged), so mark the balloon with \(-\) signs (e.g., draw several \(-\) symbols on the balloon).
• Wall: The wall is a conductor (or acts as one for static charge induction). The negative charge on the balloon induces a separation of charge in the wall: the electrons in the wall are repelled (move away from the balloon), leaving the near - side of the wall with a net positive charge. So mark the part of the wall near the balloon with \(+\) signs (e.g., draw several \(+\) symbols on the wall close to the balloon). Due to electrostatic attraction between opposite charges, the balloon will be attracted to the wall, so in diagram b, the balloon should be drawn closer to the wall (showing the attractive force).