#importing modules
import math
from __future__ import division
#Variable declaration
r=0.05; #radius of the wire(mm)
l=4; #length of the wire(cm)
e=1;
T=3000; #temperature(K)
s=5.6703*10**-8; #stefan's constant
#Calculation
A=2*math.pi*r*l*10**-5; #area(m**2)
p=s*T**4*A*e; #power radiated by the filament(W)
#Result
print "The power radiated by the filament is",round(p,2),"W"
print "answer given in the book is wrong"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=550; #wavelength(nm)
#Calculation
E=(h*c)/(lamda*10**-9); #energy of photon(J)
Es=0.1/E; #number of photons(per square cm per second)
#Result
print "The number of photons are",round(Es/10**17,2),"*10**17 per square cm per second"
print "answer in the book varies due to rounding off errors"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=300*10**-9; #wavelength(m)
e=1.6*10**-19;
phi=2.2; #work function(eV)
#Calculation
E=(h*c)/lamda; #energy of photon(J)
Kmax=(E-(phi*e))/e; #maximum kinetic energy(eV)
#Result
print "The maximum kinetic energy is",round(Kmax,2),"eV"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=175*10**-9; #wavelength of light(m)
w=5; #work function of nickel(eV)
#Calculation
E=(h*c)/(lamda*1.6*10**-19); #Energy of 200 nm photon(eV)
#From photoelectric equation E-w is the potential difference
p=E-w; #potential difference required to stop the fastest electron(eV)
#Result
print "The potential difference that should be applied is",round(p,1),"V"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
e=1.6*10**-19;
V=50; #accelerating voltage(kV)
#Calculation
lambdamin=((h*c)/(e*V*10**3))*10**9; #shortest wavelength of X-rays(nm)
#Result
print "The shortest wavelength of X-rays is",round(lambdamin,4),"nm"
#importing modules
import math
from __future__ import division
#Variable declaration
lambda1=0.708; #wavelength of a certain line in an X-ray spectrum(angstrom)
Z1=42; #atomic number
Z2=24;
a=1; #screening constant
#Calculation
lambda2=(lambda1*(Z1-a)**2)/((Z2-a)**2); #wavelength of same line(angstrom)
#Result
print "The wavelength of same line is",round(lambda2,2),"angstrom"
#importing modules
import math
from __future__ import division
#Variable declaration
#From Bragg's law 2*d*sin(teta)=n*lambda
n=1;
lamda=0.32; #wavelength(nm)
theta=28; #angle at which first order Bragg's reflection is observed(degrees)
#Calculation
theta=theta*math.pi/180; #angle(radian)
d=lamda/(2*math.sin(theta)); #distance between atomic planes(nm)
#Result
print "The distance between atomic planes is",round(d,2),"nm"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
theta=50; #angle(degrees)
m=9.1*10**-31; #mass of electron(kg)
c=3*10**8; #speed of light(m/s)
#Calculation
theta=theta*math.pi/180; #angle(radian)
deltalambda=(h/(m*c))*(1-math.cos(theta))*10**12;
lambdafin=2.5; #wavelength of scattered X-rays
lambdainit=lambdafin-deltalambda; #wavelength of X-rays in the incident beam(pm)
#Result
print "The wavelength of X-rays in the incident beam is",round(lambdainit,2),"pm"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=500*10**-9; #wavelength of laser(m)
t=20*10**-3; #time(s)
N=2.52*10**16; #number of photons in a 20ms pulse
#Calculation
E=(h*c)/lamda; #Energy of 500 nm photon(J)
p=E*N/t; #power of the laser(W)
#Result
print "The power of the laser is",round(p,1),"W"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=350*10**-9; #threshold wavelength(m)
e=1.6*10**-19;
#Calculation
W=h*c/(lamda*e); #work function of the surface(eV)
#Result
print "The work function of the surface is",round(W,2),"eV"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
e=1.6*10**-19;
lambdamin=0.02*10**-9; #minimum wavelength(m)
#Calculation
V=(h*c/(lambdamin*e))*10**-3; #accelerating voltage(kV)
#Result
print "The accelerating voltage needed to produce minimum wavelength is",round(V,4),"kV"
#importing modules
import math
from __future__ import division
#Variable declaration
#According to Bragg's eq.2*d*sin(teta)=n*lambda
n=2; #since second order Bragg's eq.
d=5; #since d=5(lambda)
lamda=1;
#Calculation
a=(n*lamda)/(2*5*lamda);
theta=math.asin(a); #angle of second order Braggs reflection(radian)
theta=theta*180/math.pi; #angle(degrees)
#Result
print "The angle of second order Braggs reflection is",round(theta,2),"degrees"
#importing modules
import math
from __future__ import division
#Variable declaration
h=6.626*10**-34; #plancks constant
c=3*10**8; #speed of light(m/s)
lamda=0.03; #wavelength(nm)
p=80/100;
#Calculation
E=(h*c)/(lamda*10**-9); #energy of photon(J)
TE=E/p; #Total energy.E=80% of TE(J)
TE=TE*(10**-3)/e; #Total energy(keV)
#Result
print "The electron must have been accelerated through a potential difference of",round(TE,3),"kV"