Charge & Coulomb’s Law
A.
Charge
1.
is the source of the _________________ ______________
2.
can neither be _____________ nor _____________ only
______________________
3.
has the SI units of _________________________
4.
is _____________________ in units of _________________
5.
comes in only __________ ___________ which are called
___________ and ____________.
6.
Like charges __________ and unlike charges ____________
B.
Terminology
1.
Neutral body is a body with ___________ amounts of
________ and __________ charge.
2.
__________________ is a material in which charge is free to
flow.
Type 1:
Type 2:
3.
________________ is a material in which charges are not
free to move.
4.
_______________ are materials between insulators and
conductors in the difficulty for charges to move.
C.
1.
Two Ways to Charge a Body
_____________ is the transfering of ______________
between two bodies due to ________________ between the
bodies.
2.
__________________ is the influencing of _____________
on a body due to a _______________ ____________ that is
nearby but _________ ______________ the 1st body.
D.
Electric Force and Gravity
Definitions:
Electric force is the force between two bodies due to
charge on the bodies
-
Gravitational force is the force between two bodies
due to the mass of the bodies
1.
Universal Law of Gravity (point/spherical masses)
2.
Coulomb’s Law (point/spherical charges)
These two formulas are important because more complicated
problems can be broken down into collections of point
masses/charges and the forces summed using superposition.
3.
Comparison
Properties
Source
Type
Range
Strength
Electric
Gravity
Mass
Attractive
∞
Weak
Problem 1:
Three charges are situated as shown below. Find
the net force upon the 1.0 nC charge.
2.0 C
0.5 m
1.0 nC
0.5 m
2.0 C
1.0 m
Solution:
Physics -
Given:
1.
Draw a Free Body Diagram
2.
Find Magnitude of Each Force
Equations:
3.
Find the Components of the Forces
4.
Add vectors by adding vector addition
5.
Draw the Resultant Vector Force
6.
Find the magnitude and angle of resultant using the
vector force diagram.
Problem 15.5 in Serway/Faughn
The nucleus of 8Be, which consists of 4 protons and 4 neutrons, is very unstable and
spontaneously breaks into two alpha particles (helium nuclei, each consisting of 2
protons and 2 neutrons). (a) What is the force between the two alpha particles when
they are 5.00x10-15m apart, and (b) what will be the magnitude of the acceleration of
the alpha particles due to this force? Note the mass of an alpha particle is 4.0026u.
Note: 1.007276 u = 1.67265x10-27 kg (Back of textbook)
Figure:
Physics:
Given:
Soultion:
Equations: