Chapter 1 Electric charge

Example 1.1 Page no 9

In [3]:
#Given
q=4.5*10**-19                       #C
e=1.6*10**-19                       #C

#Calculation
n=q/e

#Result
print"n= ",round(n,1),"This value of charge is not possible"

n=  2.8 This value of charge is not possible

Example 1.2 Page no 9

In [4]:
#Given
q=3.2*10**-7                       #C
e=1.6*10**-19                      #C

#Calculation
n=q/e

#Result
print"The required number of electrons is ",n

The required number of electrons is  2e+12

Example 1.3 Page no 9

In [17]:
#Given
q=19.2*10**-19
e=1.6*10**-19
me=9*10**-31                       #Kg

#Calculation
n=q/e
M=n*me

#Result
print"(i) The value of n=",n,"\n(ii) Charge on silk=",-q*10**19,"*10**-19"
print"(iii) Mass=",M,"Therefore mass transferred is negligibly small"

(i) The value of n= 12.0 
(ii) Charge on silk= -19.2 *10**-19
(iii) Mass= 1.08e-29 Therefore mass transferred is negligibly small

Example 1.4 Page no 9

In [8]:
#Given
a=16
n=6.023*10**23                            #C

#Calculation
W=2+a
A=((n*100)/W)*10

#Result
print"Total number of electrons in 100 g of water ", round(A,-23)

Total number of electrons in 100 g of water  3.35e+25

Example 1.5 Page no 9

In [16]:
#Given
n=10**9
e=1.6*10**-19                            #C
Q=1

#Calculation
q=n*e
t=Q/q

#Result
print (t*10**-9),"10**9 S"
print"Time required is about 198 years"

6.25 10**9 S
Time required is about 198 years

Example 1.6 Page no 13

In [24]:
#Given
q1=20                          #micro C
q2=-5                          #micro C
a=9*10**9
r=0.1  

#Calculation
q=q1+q2
q3=q/2.0
F=(a*q3*q3)/r**2

#Result
print"Force is ",round(F*10**-13,3),"N"

Force is  5.062 N

Example 1.10 Page no 14

In [66]:
#Given
m=9*10**9
q=5*10**-6
r=0.1

#Calculation
import math
F=(m*q*q)/r**2
C=2*F*math.cos(30)*(180/3.14)

#Result
print"Force on each charge is ", round(C,1)*10**-1,"N"

Force on each charge is  39.79 N

Example 1.11 Page no 14

In [79]:
#Given
m=9*10**9
q=1
r=0.24
A=20
B=12.0
m1=10**-4
g=9.8

#Calculation
import math
F=(m*q**2)/r**2
AD=math.sqrt(A**2-B**2)
C=AD/B
F1=(1/C)*m1*g
Q=math.sqrt(F1/F)

#Result
print"Charge on each sphere", round(Q*10**8,1),"10**-8","C"

Charge on each sphere 6.9 10**-8 C

Example 1.12 Page no 15

In [82]:
#Given
F=3.7*10**-9                 #C
q=1.6*10**-19                     #c
m=9*10**9
r=5*10**-10

#Calculation 
import math
n=math.sqrt(F*r**2/(m*q**2))

#Result
print round(n,0),"electrons are missing from each icon"

2.0 electrons are missing from each icon

Example 1.14 Page no 16

In [112]:
#Given
e=1.6*10**-19
m=9*10**9
G=6.67*10**-11
me=9.11*10**-31
mp=1.67*10**-27
r=10**-10

#Calculation
F0=(m*e**2)/(G*me*mp)
F1=(m*e**2)/(G*mp*mp)
F2=m*e**2/r**2
A1=F2/me
A2=F2/mp

#Result
print"(a)(i)strength of an electrons and protons", round(F0*10**-39,1)*10**39
print"   (ii)Strength of two protons ",round(F1*10**-36,1)*10**36
print"(b)    Acceleration of electron is ",round(A1*10**-22,1)*10**22,"m/s**2"
print"      Acceleration of proton is ",round(A2*10**-19,1)*10**19,"m/s*2"

(a)(i)strength of an electrons and protons 2.3e+39
   (ii)Strength of two protons  1.2e+36
(b)    Acceleration of electron is  2.5e+22 m/s**2
      Acceleration of proton is  1.4e+19 m/s*2

Example 1.16 Page no 19

In [132]:
#Given
m=9*10**9                    #C
q1=10*10**-6
q2=5*10**-6
r=0.05

#Calculation
import math
F1=m*q1*q2/r**2
F2=m*q1*q2/r**2
F3=math.sqrt(F1**2+F2**2+(2*F1*F2*math.cos(120)*180/3.14))

#Result
print"Resultant charge is ", round(F3*10**-1,0),"N"

Resultant charge is  176.0 N

Example 1.17 Page no 20

In [149]:
#Given
m=9*10**9
q1=1.2*10**-8
q2=1
r=0.03
r1=0.04
q3=1.6*10**-8

#Calculation
import math
F1=m*q1*q2/r**2
F2=m*q3*q2/r1**2
F3=math.sqrt(F1**2+F2**2)

#Result
print"Total force is ", F3*10**-5,"10**5","N"

Total force is  1.5 10**5 N

Example 1.18 Page no 20

In [168]:
#Given
m=9*10**9
q1=1
q2=100
r=10
q3=75                      #C
r1=5

#Calculation
import math
F=m*q1*q2/r**2                   #along BA
F1=m*q1*q2/r**2                   #along AC
F2=m*q3/(math.sqrt(r**2-r1**2)**2)
F3=math.sqrt(F1**2+F2**2)
X=F1/F2

#Result
print"Force experienced by 1 C Charge is ",round(F3*10**-9,2),"N"

Force experienced by 1 C Charge is  12.73 N