ENPH/PHYS 242 Fall 2013
Quiz 1 - Solution
Monday September 23, 15:30 am
Question 1: [2.5 for each correct answer; -2 for each wrong answer; minimum 0]
Which of the following comments about the ether hypothesis and the experiments discussed in
class and in

ENPH/PHYS 242 Fall 2013
Name:
Student Number:
Quiz 3 - Solution
Monday November 04, 15:30 pm
[If you feel information is missing anywhere: make a reasonable assumption and clearly state what your
assumption is]
Question 1: [4 points]
In a setup as in the

ENPH/PHYS 242 Fall 2013
Problem Set 5 - Solution
Due Monday October 21, 15:30 pm
1. Relativistic energy [a) 2; b) 2; c) 1; d) 1; e) 1]
In 1987 a supernova (exploding star) was discovered in the Large Magellanic Cloud (LMC)
which is a small galaxy 150,000

ENPH/PHYS 242 Fall 2013
Problem Set 2 - Solution
1. Binary Stars [a) 1; b) 1; c) 2]
A binary star system has a distance from Earth of 42.2 light years. The distance between the stars
is 1.08 1011 m and the rotation period is 104 days. Assume equal masses

ENPH/PHYS 242 Fall 2013
Problem Set 1 - Solution
1. Spacetime Diagram [a) 4; b) 1; c) 2]
Anna and Ben are standing 5.0 m apart when Ben pulls a paint filled balloon out of his pocket.
Anna sees this and runs away at 7.5 m/s. A second (1.0 s) later Ben thr

ENPH/PHYS 242 Fall 2016
Homework Assignment #4 - Solution
Relatively Pretty Fireworks [a) 4; b) 2; c) 3; d) 2]
It was both Newtons and Einsteins hobby to develop sophisticated fireworks. One of Newtons
masterpieces can be described as a small rocket, that

ENPH/PHYS 242 Fall 2014
Quiz 4 - Solution
Wednesday November 19, 13:30 pm
Question 1: [4]
A silicon crystal with a lattice spacing of 0.54 nm is exposed to characteristic x-rays of copper
with an energy of 8.9 k V.
a) What is the smallest angle (in degree

ENPH/PHYS 242 Fall 2016
Homework Assignment #3 - Solution
Space-mail [a) 1; b) 2; c) 2; d) 3; e) 2; BONUS: 2]
Albert owns a comfortably large spaceship with a proper length
= 99 m. He is planning on
visiting a space station with wireless internet to check

ENPH/PHYS 242 Fall 2014
Quiz 2 - Solution
Wednesday October 15, 13:30 pm
Question 1: [4 points]
A red LED emits light with a wavelength of 682 nm in all directions. It moves with a high speed relative
to an observer who sees the light being green at 551 n

ENPH/PHYS 242 Fall 2013
Name:
Student Number:
Quiz 3 - Solution
Wednesday November 05, 13:30 pm
[If you feel information is missing anywhere: make a reasonable assumption and clearly state what your
assumption is]
Question 1: [4 points]
Assume you observe

ENPH/PHYS 242 Fall 2016
Homework Assignment #7 - Solution
1. Thermal excitation in a gravitational system [ a) 1p; b) 2p; c) 1p; d) 2p ]
A crazy physicist installs a cylindrical tube in the CN tower, reaching from the bottom to highest
visitors platform a

ENPH/PHYS 242
Fall 2013
Quiz 4
Quiz 4 - Solution
Monday November 25, 15:30 pm
Question 1: [2]
The life time of the first excited state of hydrogen is
1.6
minimum uncertainty in energy (in units of V) of this state?
Heisenbergs Uncertainty Principle:

ENPH/PHYS 242 Fall 2016
Homework Assignment #8 - Solution
Thermal Radiation [ a) 1p; b) 1p; c) 4p; d) 4p ]
The emission of an incandescent light bulb is well described by a black body spectrum.
a) The most abundant wavelength is 1480 nm. What is the tempe

ENPH/PHYS 242 Fall 2016
Homework Assignment #1 - Solution
Particles and Waves [a) 1; b) 2; c) 4; d) 1; e) 2]
Three friends go out on a lake with a paddle boat. The boat is moving with = 2.0 m/s on the
shortest way towards the other shore. Exactly in the m

ENPH/PHYS 242 Fall 2016
Homework Assignment #5 - Solution
Trouble with Space Traffic [a) 4; b) 2; c) 1; d) 1; e) 2]
Albert travels in his spaceship to Spaceton (formerly also known as Space Town). As he
approaches a narrow gap between two big space statio

ENPH/PHYS 242 Fall 2016
Homework Assignment #10 - Solution
2. Bragg Reflection [a) 2; b) 3]
Bragg reflection is used to analyse the composition of the radiation form an x-ray tube. The
analysing crystal is a LiF single crystal with a lattice constant 1 of

ENPH/PHYS 242 Fall 2016
Homework Assignment #9 - Solution
1. Photoelectric Effect [a) 1; b) 1; c) 3]
We have a light source with adjustable wavelength but fixed power ( = 23.8 mW). The light is
emitted in a narrow cone, so all available power can be direc

ENPH/PHYS 242 Fall 2014
Quiz 1 - Solution
Wednesday September 24, 13:30 pm
Question 1: [5 points]
The train paradox describes a situation where light is emitted in the centre of a train. Within the
reference frame of the train the light should arrive at t

ENPH/PHYS 242 Fall 2014
Tutorial Week 2
Wednesday September 17, 13:30 pm
1. Spacetime Diagrams
a) A visit to the zoo
A lion in a cage moves with constant velocity back and forth, turning around when he
reaches the ends of his cage. A boy and a girl get to

ENPH/PHYS 242 Fall 2013
Tutorial Week 11
Monday November 25, 15:30 pm
Cross section of a Photon
We consider hydrogen gas in thermal equilibrium at
6000 K . The life-time
of the first excited state of the hydrogen atom is
1.6 10 s . The density
of states

ENPH/PHYS 242 Fall 2013
Tutorial Week 1 - Solution
Monday September 16, 15:30 pm
a) Galilean for the addition of velocities
law
vc= vc' +V vc' = vc V = 3 m/s 1 m/s = 2 m/s
V
S
S'
Student
d)
b) Since the is reflected without energy loss, the
speed before a

ENPH/PHYS 242 Fall 2013
Problem Set 3 - Solution
Due Monday October 07, 15:30 pm
Lorentz Transformation
A particle is produced in a very energetic reaction (event ). It moves away from the location of
its production (the production target) at high speed.

ENPH/PHYS 242 Fall 2013
Problem Set 4 - Solution
Due Tuesday October 15, 15:30 pm
Velocity addition [ a) 4.5p; b) 5.5p ]
240 km/h. A relatively
A relatively low speed train with a length of
100 m travels at
slow conductor moves through the train from fron

ENPH/PHYS 242 Fall 2013
Quiz 2 - Solution
Monday October 21, 15:30 pm
Question 1: [3 points]
An astronomical object emits light of a known frequency. We observe this object and measure a
frequency that is only half of the emission frequency.
a) Is this ob

39
ENPH/PHYS 242 Fall 2014
L 13
Cosmic Microwave Background
Shortly after the Big Bang the Universe was very dense and hot. Since
then it has expanded and cooled down. However, we still can measure
the thermal radiation from the Big Bang which today has a

48
ENPH/PHYS 242 Fall 2014
L 16
1.3.7 Relativistic Dynamics
The basic equation for classical dynamics is Newtons second law:
In special relativity we use the same relation between force and
momentum:
We can calculate the derivative of
explicitly a

13
ENPH/PHYS 242 Fall 2013
L 04
1.2 Speed of Light
1.2.1 Historical Introduction
To our everyday experience light seems to arrive from its source
instantaneously. For a long time in history most people believed that
this is actually true. The first docume

ENPH/PHYS 242 Fall 2014
Relativity and Quanta
Lecture Notes
Wolfgang Rau
Queens University
ENPH/PHYS 242 Fall 2014
1
ENPH/PHYS 242 Fall 2014
L 01
Introduction
At the end of the 19th century many physicists believed that the basic
problems of physics had b