In [1]:

```
#import modules
import math
from __future__ import division
#Variable declaration
q1=3.2*10**-19;
q2=q1; #q1 and q2 are the values of charge on alpha-particle(C)
d=10**-13; #distance between two alpha-particles(m)
m1=6.68*10**-27;
m2=m1; #m1 and m2 are masses of alpha-particles(kg)
G=6.67*10**-11; #Gravitational constant(Nm^2/kg^2)
#Calculation
F1=(9*10**9)*(q1*q2)/(d**2); #calculation of electrostatic force(N)
F2=G*(m1*m2)/(d**2); #calculation of electrostatic force(N)
F1=math.ceil(F1*10**4)/10**4; #rounding off to 4 decimals
F1 = F1*10**2;
#Result
print "The electrosatic force is",F1,"*10**-2 N"
print "The gravitational force is",round(F2/1e-37,3),"*10**-37 N"
```

In [2]:

```
#import modules
import math
from __future__ import division
#Variable declaration
m=9.1*10**-31; #mass of elctron(kg)
q=1.6*10**-19; #charge on electron(C)
g=9.81; #acceleration due to gravity(m/s^2)
#Calculation
Fg=m*g; #gravitational force(N)
d=math.sqrt((9*10**9*q**2)/Fg); #equating gravitational force with electrosatic force(m)
d=math.ceil(d*10**3)/10**3; #rounding off to 4 decimals
#Result
print "The distance of separation is",d,"m"
```

In [3]:

```
#import modules
import math
from __future__ import division
#Variable declaration
d=0.02; #distance between plates(m)
V=400; #potential differnce of plates(V)
q=1.6*10**-19; #charge on a proton(C)
#Calculation
E=V/d; #electric field intensity between plates(V/m)
F=q*E; #electrostatic force on oil drop(N)
#Result
print "The electric field intensity between plates is",E,"V/m"
print "The force on proton is",F,"N"
```

In [4]:

```
#import modules
import math
from __future__ import division
#Variable declaration
d=0.02; #distance between plates(m)
q=1.6*10**-19; #charge on oil drop(C)
V=6000; #potential differnce of plates(V)
g=9.81; #acceleration due to gravity(m/s^2)
#Calculation
E=V/d; #electric field intensity between plates(V/m)
F=q*E; #electrostatic force on oil drop(N)
m=F/g; #equating the weight of oil drop to the electrostatic force on it(kg)
#Result
print "The mass of oil drop is",round(m/1e-15,3),"*10**-15 kg"
```

In [5]:

```
#import modules
import math
from __future__ import division
#Variable declaration
V=150; #potential difference between anode and cathode(V)
m=9.31*10**-31; #mass of an electron(kg)
q=1.6*10**-19; #charge on an electron(C)
#Calculation
E=q*V; #energy gained by electron during speeding from cathode to anode(J)
vel=math.sqrt(E*2/m); #equating with kinetic energy of electron(m/s)
vel=vel*10**-6;
vel=math.ceil(vel*10)/10; #rounding off to 1 decimal
#Result
print "The velocity is",vel,"*10**6 m/s"
print "answer in the book is wrong by 1 decimal"
```

In [6]:

```
#import modules
import math
from __future__ import division
#Variable declaration
V=5*10**6; #potential differnce through which alpha-particle is accelerated(V)
e=1.6*10**-19; #charge on electron(C)
#Calculation
E1=2*V; #electronic charge on alpha-particle(eV)
E2=E1/10**6; #energy(MeV)
E3=E1*e; #energy(J)
E1=E1*10**-7;
#Result
print "The energy is",E1,"*10**7 eV"
print "The energy is",E2,"MeV"
print "The energy is",E3,"J"
```

In [7]:

```
#import modules
import math
from __future__ import division
#Variable declaration
r=0.528*10**-10; #radius of the orbit(m)
q=-1.6*10**-19; #charge on electron(C)
Q=1.6*10**-19; #charge on Hydrogen nucleus(C)
Eo=8.854*10**-12; #permittivity in free space(F/m)
#Calculation
E=(q*Q)/(8*3.14*Eo*r); #electric field intensity between plates(V/m)
E1=E/(1.6*10**-19); #electrifeild intensity(eV)
E=E*10**19;
E=math.ceil(E*10**2)/10**2; #rounding off to 2 decimals
E1=math.ceil(E1*10**2)/10**2; #rounding off to 2 decimals
#Result
print "The total energy is",E,"*10**-19 J"
print "The total energy is",E1,"eV"
```

In [8]:

```
#import modules
import math
from __future__ import division
#Variable declaration
Q=3.2*10**-19; #charge on alpha-particle(C)
m=6.68*10**-27; #mass on alpha-particle(kg)
B=1.5; #transverse magnetic field of flux density(Wb/m^2)
v=5*10**6; #velocity of alpha-particle(m/s)
#Calculation
F=B*Q*v; #electrostatic force on oil drop(N)
R=m*v/(Q*B); #radius(m)
R=math.ceil(R*10**2)/10**2; #rounding off to 2 decimals
R1 = R*100; #radius(cm)
#Result
print "The force on particle is",F,"N"
print "The radius of its circular path",R,"m or",R1,"cm"
```