{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# PHY 021 - PHYS 21 Spring 2011 HW 1 solutions 1 Of the...

This preview shows pages 1–2. Sign up to view the full content.

PHYS 21 Spring 2011 HW 1 solutions: 1. Of the charge Q initially on a tiny sphere, a portion q is to be transferred to a second, nearby sphere. Both spheres can be treated a particles. For what value of q / Q >0.5 will the electrostatic force between the two parts have 1/3 of the maximum possible value? Solutions for textbook version problem The magnitude of the force of either of the charges on the other is given by F q Q q r 1 4 0 2 b g where r is the distance between the charges. We want the value of q that maximizes the function f ( q ) = q ( Q q ). Setting the derivative / dF dq equal to zero leads to Q 2 q = 0, or q = Q /2. Thus, q / Q = 0.500. 10. In Fig. 21-24 four particles form a square with edge length a = 2.81 × 10 -2 m. The charges are q 1 = q 4 = 1.18 × 10 -15 C and q 2 = q 3 = q . What is q (in Coulombs) if the net electrostatic force on particle 1 is zero? Solution: For ease of presentation (of the computations below) we assume Q > 0 and q < 0 (although the final result does not depend on this particular choice).

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}