Kuwait University
Faculty of Science
Physics Department
Second Semester 2002-2003
Modern Physics 209
Final Examination
Date:
Name……………………………….. Student No. …………
1.
2.
3.
Solve all the given problems
Show detailed solution for each problem
Check the correct answer
Prob.
Marks
1
2
3
4
5
6
7
8
Total
1.
The kinetic energy of an electron is 0.459 MeV. Find its relativistic
speed.
2.
The total energy of a moving proton is three times its rest energy.
W hat is its speed during this motion?
3.
Find the speed of a particle whose total energy is 50% greater than its
rest energy.
4.
A galaxy is emitting a light with wavelength 394 nm and is moving
(receding) from Earth with a speed vo the wavelength of the light detected
on the Earth is 475 nm. W hat is the speed v of the galaxy?
5.
The cutoff frequency if v = 1.1  1015 m. W hat is the stopping potential
for iron if photoelectrons are produced by light with  = 250 nm?
6.
X-ray xo = 0.712 Å are scattered at 90 from graphite. Calculate the
fractional change in wavelength.
7.
A light source of wavelength  illuminates a metal and ejects
photoelectrons with maximum kinetic energy of 1 eV. A second light
source with half of wavelength of the first ejects photoelectrons with
maximum kinetic energy of 4 eV. W hat is the work function of the metal?
8.
An electron is accelerated from the rest through a small potential
difference V. If the de Broglie wavelength of the electron is 1.7 Å
(1.7  1015 m) calculate the potential difference.