# Chapter 26:CHARGE AND MATTER¶

## Example 26.1 Magnitude of total charges in a copper penny¶

In [5]:
from __future__ import division
import math
m =3.1 #mass of copper penny in grams
e =4.6*10** -18 #charge in coulombs
N0 =6*10**23 #avogadro’s number atoms / mole
M =64  #molecular weight of copper in gm/ mole

#Calculation
N =( N0 * m ) / M  #No. of copper atoms in penny
q = N * e  # magnitude of the charges in coulombs
print (" Magnitude of the charges in coulomb is ",q )

 Magnitude of the charges in coulombs is  133687.50000000003


## Example 26.2 Separation between total positive and negative charges¶

In [1]:
from __future__ import division
import math
F =4.5 #Force of attraction in nt
q =1.3*10**5 #total charge in coulomb
r = q * math.sqrt ((9*10**9) / F ) ;
print(" Separation between total positive and negative charges in meters is ",r )

 Separation between total positive and negative charges in meters is  5813776741.499454


## Example 26.3 Force acting on charge q1¶

In [8]:
from __future__ import division
import math
#given three charges q1,q2,q3
q1=-1.0*10**-6 #charge in coul
q2=+3.0*10**-6 #charge in coul
q3=-2.0*10**-6 #charge in coul
r12=15*10**-2 #separation between q1 and q2 in m
r13=10*10**-2 # separation between q1 and q3 in m
angle=math.pi/6 #in degrees
F12=(9.0*10**9)*q1*q2/(r12**2) #in nt
F13=(9.0*10**9)*q1*q3/(r13**2) #in nt
F12x=-F12  #ignoring signs of charges
F13x=F13*math.sin(angle);
F1x=F12x+F13x
F12y=0 #from fig.263
F13y=-F13*math.cos(angle);
F1y=F12y+F13y #in nt
print("X component of resultant force acting on q1 in nt is",F1x)
print("Y component of resultant force acting on q1 in nt is",F1y)

X component of resultant force acting on q1 in nt is 2.0999999999999996
Y component of resultant force acting on q1 in nt is -1.5588457268119893


## Example 26.4 Electrical and Gravitational force between two particles¶

In [9]:
from __future__ import division
import math
r=5.3*10**-11 #distance between electron and proton in the hydrogen atom in meter
e=1.6*10**-19 #charge in coul
G=6.7*10**-11 #gravitatinal constant in nt-m2/kg2
m1=9.1*10**-31 #mass of electron in kg
m2=1.7*10**-27 #mass of proton in kg
F1=(9*10**9)*e*e/(r**2) #coulomb's law
F2=G*m1*m2/(r**2) #gravitational force
print("Coulomb force in nt is",F1)
print("Gravitational force in nt is",F2)

Coulomb force in nt is 8.202207191171238e-08
Gravitational force in nt is 3.689889640441438e-47


## Example 26.5 Repulsive force between two protons in a nucleus of iron¶

In [2]:
from __future__ import division
import math
r=4*10**-15 #separation between proton annd nucleus in iron in meters
q=1.6*10**-19 #charge in coul
F=(9*10**9)*(q**2)/(r**2) #coulomb's law
print("Repulsive coulomb force F ",F,'nt')

Repulsive coulomb force F  14.4 nt