Practice HW 1 Solutions

Practice HW 1 Solutions - lim (kl9356) – Practice HW 1...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: lim (kl9356) – Practice HW 1 Solutions – Weathers – (22202) 1 This print-out should have 6 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Two metal spheres that are initially un- charged are mounted on insulating stands, as shown. X Y − − − − A negatively charged rubber rod is brought close to but does not make contact with sphere X . Sphere Y is then brought close to X on the side opposite to the rubber rod. Y is allowed to touch X and then is removed some distance away. The rubber rod is then moved far away from X and Y . What are the final charges on the spheres? Sphere X Sphere Y 1. Negative Negative 2. Negative Positive 3. Zero Zero 4. Positive Positive 5. Positive Negative correct Explanation: The force is repulsive if the charges are of the same sign, so when the negatively charged rod moves close to the sphere X , the neg- atively charged electrons will be pushed to sphere Y . If X and Y are separated before the rod moves away, those charges will re- main on X and Y . Therefore, X is positively charged and Y is negatively charged. 002 10.0 points 1) Two uncharged metal balls, X and Y , stand on glass rods and are touching. X Y 2) A third ball, carrying a positive charge, is brought near the first two. X Y + 3) Then the first two balls are separated from each other, X Y + 4) and the third ball is finally removed. X Y When this is all four steps are done, it is found out that 1. Ball Y is positive and ball X is negative. correct 2. Balls Y and X are both positive. 3. Balls Y and X are both negative. 4. Ball Y is negative and ball X is positive. 5. Balls Y and X are still uncharged. Explanation: Basic Concept: Electric induction caused by nearby charges. Solution: When a positive ball is moved near a metallic object ( Y and X ), the positive charge will attract negative charges, causing Y to have excess positive charge and X to have excess negative charge ( Y and X are in lim (kl9356) – Practice HW 1 Solutions – Weathers – (22202) 2 contact, so the total net charge on Y and X should be zero).- + + Later, Y and X are separated, retaining their charges, so when the third ball is finally removed, Y will have net positive charge and X will have net negative charge....
View Full Document

This note was uploaded on 09/07/2010 for the course PHYS 2220 taught by Professor Littler during the Spring '00 term at North Texas.

Page1 / 6

Practice HW 1 Solutions - lim (kl9356) – Practice HW 1...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online