• Calculated the electrostatic force between two point charged, such as electrons or protons
• Given a collection of points, find the position where the net force on a test charge equals 0
• Create a real-world environment given a minimally working code
• Graph the relationship between net force and position of a test charge

• Coulomb's law
  • $F=k\dfrac{q_1q_2}{r^2}$
• Vector mathematics
• Principle of superposition

• Copy/paste code
• Modify existing code
• while loops and if statements
• Translate physical qualities and equations into code

—-

Charged Particles

Where should a particle be placed around two charged particles so that the total force acting on the particle is zero. Open the minimally working code (below) and answer the following questions:

1. Where are Charge 1, Charge 2, and the Test Charge initially located?
2. What is the charge on Charge 1? Charge 2? the Test Charge?
3. Based on the charges, will the force of Charge 1 on the Test Charge be attractive or repulsive?
4. Based on the charges, will the force of Charge 2 on the Test Charge be attractive or repulsive?
5. Which force do you expect to be stronger?

Now within your program, develop an equation to calculate the force on your test particle by Charge 1. Likewise, develop an equation to calculate the force on your test particle by Charge 2. Using the forces you calculated, create an equation for the net force on your test particle, and subsequently the acceleration of the test particle. Use the acceleration to update the position of the particle within the while loop. Lastly, graph the force on the test particle with respect to distance from Charge 1, and do the same with Charge 2.

GlowScript 2.7 VPython
#Created by Meagan Brasseur, Sofia Villanueva, and John Plough on August 9,2019
#Debugged by Dan Weller August 17,2019
#Code is still INCOMPLETE
 
##Objects##
Charge1 = sphere(pos=vec(0,0,0), radius=0.1, color=color.cyan)
Charge2 = sphere(pos=vec(5,0,0), radius=0.1, color=color.cyan)
Tcharge = sphere(pos=vec(2.5,2.5,0), radius=0.05, color=color.red)
 
#Coulombic charges of our spheres
 
q1    = 6.0*10**(-19)
q2    = 6.0*10**(-19)
qt    = -1.6*10**(-19)
 
##Constants##
k = 9*10**9
mTest = 9.11*10**(-31)
vTest = vec(0,0,0)
 
## Create graphs to track force
Grph1 = graph(title='Force (1) v Distance', xtitle='Distance (m)', ytitle='Force (N)', fast=False, ymin=-1.4E-28, ymax=-1.3E-28) #initialize our graphs.
F1Graph = gcurve(color=color.green, label='Force of Charge 1 on Test Charge') #Make a graph for the force on the test charge with respect to distance from Charge1.
 
Grph1 = graph(title='Force (2) v Distance', xtitle='Distance (m)', ytitle='Force (N)', fast=False, ymin=1.4E-28, ymax=1.3E-28) #initialize our graphs.
F2Graph = gcurve(color=color.green, label='Force of Charge 2 on Test Charge') #Make a graph for the force on the test charge with respect to distance from Charge2.
 
#Set up time variables for while loop
t=0
dt=1*10**(-4)
tf=1
 
#While loop to iterate over the time interval
 
while t < tf:
    rate(100)
# Defines the rate at which the program runs #
 
##Hint: For the following calculations, break them up into components!##
 
#Come up with an equation for the force on your test charge from Charge 1
 
    F1tx = k*q1*qt/((Tcharge.pos.x-Charge1.pos.x)**2)
 
    if Tcharge.pos.x <= Charge1.pos.x : 
        F1tx = -F1tx
 
    F1ty = k*q1*qt/(((Tcharge.pos.y)-(Charge1.pos.y))**2)
 
    if Tcharge.pos.y <= Charge1.pos.y : 
        F1ty = -F1ty
 
    F1tz = k*q1*qt/((Tcharge.pos.z-Charge1.pos.z)**2)
 
    if Tcharge.pos.z <= Charge1.pos.z : 
        F1tz = -F1tz
 
    F1t = vec(F1tx,F1ty,F1tz)
 
#    print("F1t = ", mag(F1t))
 
##Come up with an equation for the force on your test charge from Charge 2
 
    F2tx = k*q2*qt/(((Tcharge.pos.x)-(Charge2.pos.x))**2)
 
    if Tcharge.pos.x <= Charge2.pos.x : 
        F2tx = -F2tx
 
    F2ty = k*q2*qt/(((Tcharge.pos.y)-(Charge2.pos.y))**2)
 
    Tcharge.pos.y <= Charge2.pos.y : 
        F2ty = -F2ty
 
    F2tz = k*q2*qt/(((Tcharge.pos.z)-(Charge2.pos.z))**2)
 
    Tcharge.pos.z <= Charge2.pos.z : 
        F2tz = -F2tz
 
    F2t = vec(F2tx,F2ty,F2tz)
#
##Come up with an equation for the net force on your test charge from both charges
#
    Fnetx = F1tx + F2tx
    Fnety = F1ty + F2ty
    Fnetz = F1tz + F2tz
 
    Fnet = vec(Fnetx,Fnety,Fnetz)
 
#Come up with an equation for the net acceleration of your test charge from both charges
 
    at = vec(Fnetx/mTest,Fnety/mTest,Fnetz/mTest)
 
    at = vec((F1tx)/mTest,0,0)
 
#Update the position of the test charge using the equation you came up with for acceleration. 
 
    vTest = vTest + at*dt
 
    Tcharge.pos = Tcharge.pos + vTest*dt 
 
 
#Graph the Net Force on the Test charge with regards to position. 
 
    F1Graph.plot(mag(Tcharge.pos),mag(F1t))
    F2Graph.plot(mag(Tcharge.pos),mag(F2t))
 
    t = t + dt