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Electricity and Magnetism

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Length of a Line of Charge: Field Point Above the Edge

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Figure 1 depicts a line of charge of length $l$, upon which a linear charge density of $\lambda = 2.08 \: \rm \frac{nC}{m}$ has been placed.

Figure 1. Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.

A field point $P$ exists a distance $z$ above the left edge of the line of charge. Figure 2 shows the electric potential $V$ at the field point as a function of the transverse displacement $z$ of the field point from the line.

Figure 2. Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.

What is the length $l$ of the line of charge?

A

$l = 5.41 \text{ cm}$

B

$l = 6.43 \text{ cm}$

C

$l = 5.00 \text{ cm}$

D

$l = 4.68 \text{ cm}$