Physics 215 – Fall 2006
Name: ______________________
Homework Journal #1:
Charge Conservation / Intro Coulomb’s Law & E Fields
Instructor: ___________________
Section:
Date Due: T3 / M4
M1 M2 M3 M4 M5 M6
T1 T2 T3 T4 T5 T6
INSTRUCTIONS: To receive full credit, you must fully justify your answers and show all written
work (including algebraic steps) in a neat and orderly fashion. If your work is disorganized or the
grader cannot follow you logic, you will be penalized. Avoid writing down single answer solutions –
the homework problems, like the GRs, are generally designed to require multiple steps and, with only a
few exceptions, are not “plug and chug” exercises.
AUTHORIZED RESOURCES: Please document any instructor(s) and/or student(s) you consulted
and the precise nature of the assistance you received in completing this assignment. You DO NOT
need to document use of the text, class handouts, or your own classroom instructor. Any published or
unpublished material, or internet source, does not need to be documented unless the material
specifically aims at answering problems in Mastering Physics.
DOCUMENTATION:
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Problem Name
Points
Possible
Points
Earned
Problem Name
Knight Problem 25.1
Knight Problem 25.14
Knight Problem 25.2
Knight Problem 25.50
Knight Problem 25.3
CP 1.7
Knight Problem 25.32
CP 1.8
Total:
_______ / 34
1/9
Points
Possible
Points
Earned
Problem Name: Knight Problem 25.1
Description: A glass rod is charged to ____________ by rubbing.
How many electrons have been removed or protons added?
Answer:
Physics 215 – Fall 2006
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Problem Name: Knight Problem 25.2
Description: A plastic rod is charged to ____________ by rubbing.
How many electrons have been added or protons removed?
Answer:
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Problem Name: Knight Problem 25.3
Description: A _________ diameter copper ball is charged to _____________.
What fraction of its electrons have been removed?
Answer:
Physics 215 – Fall 2006
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Problem Name: Knight Problem 25.32
Description: Two identical metal spheres A and B are connected by a metal rod. Both are
initially neutral. ___________ electrons are added to sphere A, then the
connecting rod is removed.
Part A: Afterward, what is the charge of A?
Answer:
Part B: and the charge of B?
Answer:
Physics 215 – Fall 2006
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Problem Name: Knight Problem 25.14
What is the net electric force on charge A in the figure?
Answer:
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Problem Name: Problem 25.50
Part A: Charge q2 is in static equilibrium. What is q1?
Answer:
Part B: What is the electric field at the location of charge q2?
Answer:
Physics 215 – Fall 2006
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Problem Name: CP 1.7
Description: An electron and a proton are separated and held a distance of ________ mm apart.
Part A: If they are suddenly released, what will be the instantaneous acceleration of the proton?
Answer:
Part B: At this same time, what will be the instantaneous acceleration of the electron?
Answer:
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Problem Name: CP 1.8
Description: In an electric field ________ kN/C, a particle experiences a force _________ N.
Part A: What is the charge of the particle?
Part B: Using your answer from Part A, determine how many electrons have been added to (or are
missing from) that particle?
Physics 215 – Fall 2006
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