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What is the best explanation for the observation that the electric charge on the stem became positive as the charged bee approached (before it landed)? (a) Because air is a good conductor, the positive charge on the bee's surface flowed through the air from bee to plant. (b) Because the earth is a reservoir of large amounts of charge, positive ions were drawn up the stem from the ground toward the charged bee. (c) The plant became electrically polarized as the charged bee approached. (d) Bees that had visited the plant earlier deposited a positive charge on the stem.

Short Answer

Expert verified
The best explanation is option (c): plant polarization.

Step by step solution

01

Understanding the Question

We need to determine which choice explains why the electric charge on the plant stem became positive as a charged bee approached it, even before the bee landed.
02

Analyzing Option (a)

Option (a) suggests that the charge was transferred through the air because air is a good conductor. However, air is actually a poor conductor, making this option unlikely to explain the observation.
03

Analyzing Option (b)

Option (b) claims positive ions are drawn up the stem from the ground. While the Earth is a charge reservoir, this option implies charge movement that’s not typically how charge redistribution due to external fields occurs.
04

Analyzing Option (c)

Option (c) involves polarization, where the charged bee induces a separation of charges in the plant, leading to charges on the stem becoming positive near the bee without direct contact. This explanation aligns with known physical behavior of polarization.
05

Analyzing Option (d)

Option (d) states that previous bees left a positive charge on the stem. However, this doesn’t explain why the charge became positive as the current bee approached.
06

Conclusion

The best explanation is option (c): The plant became electrically polarized as the charged bee approached, causing charges to rearrange and the observed positive charge on the stem.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Electric Charge
Electric charge is one of the fundamental properties of matter. It comes in two types: positive and negative. Objects become charged when they gain or lose electrons, the negatively charged particles that orbit an atom's nucleus.

If an object gains electrons, it becomes negatively charged, whereas if it loses electrons, it becomes positively charged.
  • Like charges repel each other.
  • Opposite charges attract each other.
These interactions are what lead to various phenomena, including electric forces and the ability of charged objects to exert force over a distance.
Conductors and Insulators
Materials can be classified as conductors or insulators based on their ability to allow electric charge to move through them. Conductors, like metals, allow charges to flow freely. This is because they have free electrons that can move easily within the material’s structure.

On the other hand, insulators, such as rubber or glass, do not allow charge to flow easily. This is because their electrons are tightly bound to their atoms, making movement difficult.
  • Conductors: Facilitate easy movement of charge.
  • Insulators: Restrict the movement of charge.
Understanding the nature of conductors and insulators helps in explaining how charge can build up on an object or get transferred between them.
Charge Redistribution
Charge redistribution occurs when charges within a conductor move in response to other nearby charges. When a charged object is brought near a conductor, the free electrons in the conductor move, causing a shift in charge distribution.

This process is especially important in explaining how conductive materials can become polarized. Charge redistribution does not necessarily mean the conductor gains or loses charge but rather that charges within it realign under external influence. Consequently, this can result in localized regions of positive or negative charge depending on where the external charge is positioned relative to the conductor.
Induced Charge Separation
Induced charge separation is the process by which a charged object causes a redistribution of charges within another object, even without directly touching it. When a charged object, like a bee, approaches a neutral object, like a plant stem, it can cause the charges in the neutral object to rearrange.

In this case, the charged bee induces positive and negative charges to separate within the plant, resulting in one side of the plant becoming positively charged and the other negatively charged. This polarization effect is a crucial concept in understanding how objects can influence each other's electrical state from a distance, aligning with option (c) from the exercise. This happens because electric fields from charges extend into space and exert forces on electric charges over distances.

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Most popular questions from this chapter

A straight, nonconducting plastic wire 8.50 cm long carries a charge density of \(+\)175 nC\(/\)m distributed uniformly along its length. It is lying on a horizontal tabletop. (a) Find the magnitude and direction of the electric field this wire produces at a point 6.00 cm directly above its midpoint. (b) If the wire is now bent into a circle lying flat on the table, find the magnitude and direction of the electric field it produces at a point 6.00 cm directly above its center.

(a) An electron is moving east in a uniform electric field of 1.50 N\(/\)C directed to the west. At point \(A\), the velocity of the electron is 4.50 \(\times 10^5\) m\(/\)s toward the east. What is the speed of the electron when it reaches point B, 0.375 m east of point A? (b) A proton is moving in the uniform electric field of part (a). At point \(A\), the velocity of the proton is 1.90 \(\times 10^4\) m\(/\)s, east. What is the speed of the proton at point \(B\)?

Four identical charges \(Q\) are placed at the corners of a square of side \(L\). (a) In a free-body diagram, show all of the forces that act on one of the charges. (b) Find the magnitude and direction of the total force exerted on one charge by the other three charges.

The earth has a net electric charge that causes a field at points near its surface equal to 150 N\(/\)C and directed in toward the center of the earth. (a) What magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth's electric field? (b) What would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? Is use of the earth's electric field a feasible means of flight? Why or why not?

In a follow-up experiment, a charge of \(+40\) pC was placed at the center of an artificial flower at the end of a 30-cm long stem. Bees were observed to approach no closer than 15 cm from the center of this flower before they flew away. This observation suggests that the smallest external electric field to which bees may be sensitive is closest to which of these values? (a) \(2.4 \space N/C; (b) 16 \space N/C; (c) 2.7 \times 10^{-10} \space N/C; (d) 4.8 \times 10^{-10} \space N/C.\)

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