Name : Mohamed fawaz
ID#:114454192
This activity consists of two Parts
Part one: Eclectic force versus distance.
Part two: Electric forces versus charge.
To be familiar with the electrostatic force magnitude direction and the parameters affect this
force using Phet simulation open the following link and play with it.
https://phet.colorado.edu/sims/html/coulombs-law/latest/coulombs-law_en.html
Objectives:
1- Satisfy Coulomb’s law experimentally
2- Study the parameters that affect the electric force. (distance and charge
3- Find experimentally the electric constant k
Theoretical Background:
Coulomb’s Law: “The magnitude of the electric force that a particle exerts on another is directly
proportional to the product of their charges and inversely proportional to the square of the distance
between them.” Mathematically, the magnitude of this electrostatic force FE acting on two charged
particles (q1, q2) is expressed as:
𝑞 𝑞
FE = k 1 2
𝑟2
Where r is the separation distance between the charged objects and k is a constant of proportionality,
called the Coulomb constant, k = 9.0 × 109 Nm2/C2.
Part one:
To satisfy the objectives do the following steps.
1- Click on the following link and fix the charge q1 and q2 write their values in the table 1.
https://phet.colorado.edu/sims/html/coulombs-law/latest/coulombs-law_en.html
2- Change the distance between the two charges as shown in the table 1.
3- Record the force value for each distance.
4- Fill table 1 by finding r2 and 1/r2.
1
q1=……2…….
r (cm)
r2 (m2)
0.01
10
0.0081
9
0.0064
8
0.0049
7
0.0036
6
0.0025
5
0.0018
4
0.0009
3
Table 1 (24 points )
q2=………4….
2
FE (N)
1/r (1/m2)
100
123.46
156.25
204.08
277.78
400
625
1111.12
7.190
8.877
11.234
14.674
19.971
28.760
44.938
74.818
Part two:
To satisfy the objectives do the following steps.
1- Click on the following link and fix the charge q1 and the distance r, write their values in the
table 1.
https://phet.colorado.edu/sims/html/coulombs-law/latest/coulombs-law_en.html
2- Control q1 and fix it at 5c and fix the distance between the two objects at 6 cm, record them
in table 2.
3- Change the charge of object 2 as shown in the table 2 and for each q2 record the electric force
between the two objects in table 2.
Table 2 (8 points)
q1 = 5 C
r=6 cm
q2 (C)
FE (N)
124.827
10
112.344
9
99.862
8
87.379
7
74.896
6
62.414
5
49.931
4
37.449
3
Data Analysis
Part one:
1- Uses excel software and plot a graph relates FE and r. comments on the graph. [10 points]
2- Uses excel and plot one more graph relates FE and 1/r2. Use the graph to find the electric
constant k. [4points]
………………………………………………………………………………………………
2
Fe Vs r
44,93
19,972
11,234
7,19
0.1M
0.08M
0.06M
0.04M
Fn(N)
………………………………………………………………………………………………
………………………………………………………………………………………………
3- Calculate the percentage error in k (kknown=9.0 × 109 Nm2/C2) [4points]
the percentage error in this case would be approximately 2.22%
………………………………………………………………………………………………
………………………………………………………………………………………………
Fe Vs 1/r^2
50
45
40
35
30
25
20
15
10
5
0
100m
156.25
277.78
625
Fn(N)
………………………………………………………………………………………………
3
Note: Attach the graphs to your sheet
Part two:
1- Uses excel software and plot a graph relates FE and q2. comments on the graph. [10 points]
2- Use the graph to find the electric constant k. [4 points]
Fe Vs q2
124,827
99,862
74,0896
49,931
10UC
8UC
6UC
4
Fe(N)
…
……………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
3- Calculate the percentage error in k (kknown=9.0 × 109 Nm2/C2) [4 points]
………………………………………………………………………………………………
The percentage error is exactly 2.2%
………………………………………………………………………………………………
………………………………………………………………………………………………
Note: Attach the graphs to your sheet
4