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WorksheetsTurning points quiz
Total questions: 1
Worksheet time: 57mins
Who discovered that gases at sufficiently low pressure in sealed glass tubes conduct electricity and glow with light of a characteristic color?
J.J. Thomson
Ernest Rutherford
Niels Bohr
William Crookes
What observation did William Crookes make about the glowing gas in a discharge tube?
The glowing gas near the anode is called the positive column
The glowing gas near the cathode is called the negative glow
The glowing gas near the anode is called the negative column
The glowing gas near the cathode is called the positive glow
What did the 'paddle wheel' experiment demonstrate about cathode rays?
Cathode rays have no mass and no charge
Cathode rays are positively charged particles
Cathode rays are capable of moving through a gas and causing a paddle wheel to rotate
Cathode rays are unaffected by magnets
What did Joseph J Thomson prove about cathode rays?
Cathode rays are made up of protons
Cathode rays are made up of neutrons
Cathode rays are made up of positively charged particles
Cathode rays are made up of negatively charged particles
What causes the emission of light from a discharge tube?
The high voltage applied to the tube ionises some of the gas atoms
The low voltage applied to the tube ionises some of the gas atoms
The neutral atoms in the tube emit light without any voltage
The cathode rays emit light when they hit the anode
What is the 'negative glow' in a discharge tube due to?
Electrons emitted from the cathode surface
Photons emitted when some of the positive ions and electrons recombine
The reflection of light from the anode
The absorption of light by the cathode
What term was used to describe electrons that are attracted to the anode and move away from the cathode in a discharge tube?
Anode rays
Cathode rays
Excitation rays
Conduction rays
What causes the positive column of glowing gas in a discharge tube?
De-excitation of excited gas atoms
Recombination of electrons with gas atoms
Emission of photons of visible light
Collision of electrons with the anode
What is thermionic emission?
The emission of electrons when a gas is heated
The emission of electrons when a metal is heated
The emission of photons from a metal surface
The emission of electrons due to a high voltage
What is the role of the anode in thermionic emission?
It emits electrons when heated
It accelerates the electrons to form a narrow beam
It recombines with the electrons
It provides the kinetic energy to the electrons
According to the document, what is the relationship between the work done by the potential difference V and the kinetic energy of an electron?
V = ½ mv²
eV = ½ mv²
eV = mv
V = mv
For the equation e/m = 2V/B²r² to be valid, what must be true about the speed of the electrons?
The speed of the electrons must be equal to the speed of light in free space, c.
The speed of the electrons must be much less than the speed of light in free space, c.
The speed of the electrons must be much greater than the speed of light in free space, c.
The speed of the electrons is not relevant to the validity of the equation.
What did Thomson find about the specific charge of the electron compared to that of the hydrogen ion?
It was the same as the hydrogen ion.
It was much smaller than that of the hydrogen ion.
It was much larger than that of the hydrogen ion.
It was irrelevant to the hydrogen ion.
What provides the centripetal force for an electron moving in a magnetic field according to the document?
The electric force due to the anode voltage supply.
The gravitational force acting on the electron.
The magnetic force on each electron (-Bev).
The force due to the filament voltage supply.
Which of the following expressions is used to derive the specific charge (e/m) of the electron?
e/m = 2V/B²r²
e/m = mv²/r
e/m = Bev
e/m = V/Br²
Why is no work done on the electrons by the magnetic field?
Because the magnetic field does not exert any force on electrons
Because the force by the magnetic field is parallel to the direction of movement
Because the force by the magnetic field is at a 90° angle to the direction of movement
Because the electrons are stationary
What should you find to determine the velocity of an electron in a magnetic field?
Two expressions for velocity (v)
Two expressions for acceleration (a)
Two expressions for velocity squared (v^2)
Two expressions for work done (W)
What is the arrangement of electric and magnetic fields where the force due to the magnetic field is balanced by the force due to the electric field called?
Parallel fields
Crossed fields
Balanced fields
Unidirectional fields
When the electric field (E-field) is switched on and adjusted to straighten out the beam, what is the relationship between the electric force (Fe) and the magnetic force (Fb)?
Fe < Fb
Fe > Fb
Fe = Fb
Fe and Fb are unrelated
According to the method described, what is the correct expression for the radius of curvature (r) when the E-field is switched off?
(a)
What can be measured to find the specific charge (e/m) of an electron?
What is the deflection, y, of the beam at the edge of the plates measured for?
The time taken by each electron to pass between the plates
The speed of the electrons
The acceleration of each electron towards the positive plate
The measured plate pd, Vp
How is the speed, v, of the electrons measured?
By the time taken by each electron to pass between the plates
By using a magnetic field B perpendicular to the beam
By the measured deflection y
By the plate separation d
What equation is used to calculate the acceleration, a, of each electron towards the positive plate?
y = ½ a t²
a = F/m = e V/md
e/m = ad/V
t = L/v
What does e/m represent in the context of the experiment?
The time taken by each electron to pass between the plates
The speed of the electrons
The acceleration of each electron towards the positive plate
The value of the charge-to-mass ratio of an electron
How can the value of e/m be determined from the experiment?
e/m = L/v
e/m = ad/V
e/m = V/md
e/m = y/t²
What is the relationship between the electric force and the weight of the oil droplet when it is held stationary by a vertical electric field according to Millikan's experiment?
The electric force is greater than the weight of the oil droplet.
The electric force is less than the weight of the oil droplet.
The electric force is equal to the weight of the oil droplet.
There is no relationship between the electric force and the weight of the oil droplet.
What is the formula for the weight of the oil droplet when it is stationary in a vertical electric field?
mg = QV
mg = QV/d
mg = d/QV
mg = Q/dV
What happens to the oil droplet when it falls at terminal speed with no electric field present?
It accelerates continuously.
It falls at a constant speed.
It stops falling.
It falls with increasing acceleration.
According to Stokes' Law, what is the relationship between the drag force and the weight of the oil droplet falling at terminal speed?
The drag force is greater than the weight of the oil droplet.
The drag force is less than the weight of the oil droplet.
The drag force is equal to the weight of the oil droplet.
The drag force and the weight of the oil droplet are not related.
What can be calculated if the values of the speed v, the oil density ~, and the viscosity of air are known?
The mass of the oil droplet.
The charge of the electron.
The radius of the oil droplet.
The electric field strength.
Who first suggested that light had a finite speed based on astronomical observations in 1676?
Isaac Newton
Albert Einstein
Galileo Galilei
Ole Rømer
In Fizeau's experiment for determining the speed of light, what was used to measure the time taken for light to travel to a mirror and back?
A pendulum
A water clock
A toothed wheel
A stopwatch
What happened to the beam of light in Fizeau's experiment when the speed of rotation of the toothed wheel was doubled?
The beam of light could not pass through any gaps.
The beam of light was blocked by two adjacent teeth.
The beam of light passing through gap 0 could pass through gap 1 on return.
The beam of light was completely absorbed by the wheel.
What was the distance from the point of origin of the light to the mirror in Fizeau's arrangement?
8.6 km
12.6 km
3.13 x 10^8 m/s
720 km
How many teeth and gaps did Fizeau's wheel have?
720 teeth and 720 gaps
360 teeth and 360 gaps
8.6 teeth and 8.6 gaps
12.6 teeth and 12.6 gaps
What did Fizeau find to be the speed of light from his experiment?
12.6 revolutions per second
3.13 x 10^8 m/s
8.6 km/s
720 m/s
What phenomenon did scientists find when measuring the speed of light in moving water?
Light travelled quicker when emitted in the direction of flow than against it.
Light speed was the simple sum of light speed in water plus the speed of the fluid.
Light speed in water was the same as in air.
Light could not exist in free space.
Which theory was supported by the findings that the speed of light in water was not a simple sum of the speed of light in water plus the speed of the fluid?
Newton's corpuscular theory
Fizeau's wheel theory
Einstein's theory of relativity
Hertz's wave theory
What did Maxwell's theory predict before there was experimental evidence for electromagnetic waves?
What did the separate discoveries of X-rays and radio waves confirm?
What did Hertz use to detect radio waves?
A single metal rod
A wire loop with a small gap
A concave metal sheet and two metal rods
A flat metal sheet
What did Hertz discover about the reflection of radio waves?
They are reflected by a flat metal sheet
They are not reflected by any metal surfaces
They are absorbed by concave reflectors
They are only reflected by insulators
What property of radio waves did Hertz demonstrate through his experiments?
That they are unpolarised
That they are polarised
That they cannot be detected
That they are always stationary
What does the ultraviolet catastrophe refer to?
The agreement between practical measurements of energy intensity and classical physics predictions
The disagreement between practical measurements of energy intensity and classical physics predictions
The exact match of observed spectrum with classical prediction
The phenomenon where ultraviolet radiation is not emitted by black bodies
According to classical physics, how was the energy from a black body expected to be emitted?
Evenly across all wavelengths
Mostly at long wavelengths
Mostly at short (ultraviolet) wavelengths
Only at a single wavelength
What discrepancy did measurements reveal about black body radiation compared to classical predictions?
Measurements showed a constant energy intensity across all wavelengths
Measurements showed no energy emitted at ultraviolet wavelengths
Measurements showed a peak in energy intensity at a certain wavelength
Measurements confirmed the classical prediction of infinite energy at very short wavelengths
According to Planck's theory, what is the relationship between the energy quantum and frequency?
The energy quantum is inversely proportional to frequency.
The energy quantum is directly proportional to frequency.
The energy quantum is unrelated to frequency.
The energy quantum is the square of the frequency.
What phenomenon did Einstein explain using the photon theory of light?
Thermionic emission
Photoelectric emission
Radio wave propagation
Metal heating
What happens when the frequency of the incident light is below the threshold frequency in photoelectric emission?
Photoelectric emission occurs at maximum kinetic energy.
Photoelectric emission occurs instantaneously.
Photoelectric emission does not occur.
Photoelectric emission occurs with a range of kinetic energies.
What did investigations of photoelectric emission show regarding the kinetic energies of photoelectrons?
They have a fixed kinetic energy.
They have a range of kinetic energies from zero up to a maximum value.
They have a kinetic energy that is independent of the metal type.
They have a kinetic energy that decreases with the intensity of incident light.
Why does the wave theory of light fail to explain the photoelectric effect?
It cannot explain the threshold frequency.
It predicts a delay in emission that is not observed.
It suggests that light intensity is the only factor affecting emission.
Both A and B are correct.
What must a conduction electron absorb to escape from a metal according to Einstein's theory?
Multiple photons
A single photon
Thermal energy
Kinetic energy
What is the kinetic energy of emitted electrons given by?
Ek = hf
Ek = Φ
Ek = hf - Φ
Ek = eVs
What is the threshold frequency of the incident radiation, f₀, equal to?
f₀ = Ek / h
f₀ = Φ / h
f₀ = eVs / h
f₀ = hf / Φ
What happens to the number of photoelectrons emitted per second as the potential of the metal becomes more positive?
It increases indefinitely
It remains constant
It decreases
It first increases, then decreases
What is the stopping potential, Vs, defined as?
The potential at which the kinetic energy of photoelectrons is maximum
The potential at which the kinetic energy of photoelectrons is zero
The potential at which the number of photoelectrons emitted is maximum
The potential at which the thermal energy of electrons is zero
What is the relationship between the stopping potential (Vs) and the frequency (f) of incident radiation as shown in the graph?
It is a parabolic curve
It is an exponential curve
It is a straight line with a gradient
It is a hyperbolic curve
For what contribution was Einstein awarded the 1921 Nobel Prize in Physics?
For his theory of relativity
For his explanation of Brownian motion
For his photon theory of light
For his work on the quantum theory of solids
What dual nature is observed in photons according to Einstein's explanation?
Wave and particle
True
False
Static and dynamic
Who invented the transmission electron microscope?
James Watson and Francis Crick
Max Knoll and Ernst Ruska
Marie Curie and Pierre Curie
Albert Einstein and Niels Bohr
What did Max Knoll and Ernst Ruska realize about electron waves?
They could be used to generate electricity
They had no practical application
They could produce much higher resolving power than light waves in an optical microscope
They were identical to light waves in an optical microscope
What is the magnification capability of the latest transmission electron microscopes (TEMs)?
10 times magnification
107 times magnification
1000 times magnification
10,000 times magnification
What is the function of electromagnetic lenses in a transmission electron microscope?
To reflect electrons back to the source
To scatter electrons uniformly across the sample
To deflect electrons towards the axis of the microscope
To convert electrons into visible light
What is the smallest size of the images that the latest TEMs can enable to be seen?
About 1 nm
About 0.1 mm
About 0.1 nm
About 1 µm
How are electrons produced in a transmission electron microscope?
Nuclear fission
Thermionic emission from a filament wire
Photovoltaic effect
Chemical reaction
What is the acceleration voltage range for electrons in a transmission electron microscope?
5–10 kV
15–20 kV
50–100 kV
200–300 kV
What determines the amount of detail in the image produced by an electron microscope?
The size of the sample
The resolving power which is related to the wavelength of the electrons
The brightness of the fluorescent screen
The type of sample being observed
What is the effect of increasing the electron speed on the wavelength and the resulting image detail in an electron microscope?
The wavelength increases and the image detail decreases
The wavelength decreases and the image detail increases
The wavelength and image detail both increase
The wavelength and image detail both decrease
What is limited by lens aberrations in an electron microscope?
The ability to focus electrons from each point on the sample to a point on the screen
The speed at which the electrons travel through the microscope
The thickness of the sample being observed
The amount of light that reaches the fluorescent screen
What is the name of the most powerful electron microscope mentioned in the text?
The TEAM 0.5 electron microscope
The Scanning Tunneling Microscope (STM)
The Aberration Corrector Microscope
The Lawrence Berkeley Laboratory Microscope
What year was the Scanning Tunneling Microscope (STM) invented?
1971
1981
1991
2001
In constant current mode of the STM, what happens when the probe tip moves and the current changes?
The probe's vertical position changes to maintain the same current
The image of the surface is generated without changing the probe's vertical position
The gap width between the probe and the surface is altered
The tunneling current remains constant regardless of the probe's position
What is the vertical resolution of the Scanning Tunneling Microscope (STM)?
0.1 nm
0.01 nm
0.001 nm
1 nm
What is the principle of quantum tunneling based on?
The particle nature of light
The wave nature of particles
The amplitude of light waves in a barrier
The width of the barrier
What happens to the amplitude of matter waves in a barrier during tunneling?
It is reduced to zero by the passage of light in the film
It becomes zero if the barrier is wide enough
It does not become zero if the barrier is sufficiently narrow
It increases with the width of the barrier
What is the approximate 'de Broglie wavelength' of an electron in a metal at room temperature?
0.001 nm
1 nm
10 nm
100 nm
For what gap widths is tunneling possible according to the text?
Gaps of the order of 10 nm
Gaps of the order of 1 nm or so
Gaps of the order of 0.1 nm
Gaps of the order of 0.001 nm
What is sensitive to changes of the gap width as little as 0.001 nm?
The amplitude of light waves
The 'de Broglie wavelength' of an electron
The tunneling current
The barrier width
What does the vertical piezoelectric transducer control in a Scanning Tunneling Microscope (STM)?
The horizontal movement of the rod
The vertical movement of the rod
The tunneling current
The potential of the probe tip
What is the function of the probe tip in a Scanning Tunneling Microscope (STM)?
It controls the vertical movement of the rod
It scans the sample horizontally
It is kept at a small constant potential to allow electrons to tunnel across the gap
It increases the 'de Broglie wavelength' of electrons
What does each bright dot in the image represent in the reconstruction of the III-V semiconductor surface?
The position of an indium (In) atom
The position of an antimonide (Sb) atom
The position of a molecule of InSb
A defect in the semiconductor surface
How are the Sb atoms arranged on the (100) surface of indium antimonide (InSb) as shown in the image?
In pairs
In groups of three in a brickwall-like structure
In a linear chain
Randomly scattered
What is the semiconductor surface shown in the image an example of?
The lowest spatial resolution achievable from this class of materials
The best spatial resolution achievable from this class of materials
A theoretical model of a semiconductor surface
A poorly reconstructed semiconductor surface
What is the result of analyzing the consequences of the absence of any universal frame of reference, according to Einstein's theory of special relativity?
It leads to the concept of absolute time and space.
It results in the theory of special relativity, which concentrates on inertial frames of reference.
It disproves the theories of classical mechanics.
It establishes a universal frame of reference as the absolute standard.
Special relativity is based on how many postulates?
One
Two
Three
Four
Which of the following is NOT one of the postulates of special relativity?
The laws of physics have the same form in all inertial frames.
The speed of light in free space is invariant for all observers.
The laws of physics are expressed in equations.
What was the Michelson-Morley experiment trying to determine?
The relative speed of light in different inertial frames.
The effects of gravity on the speed of light.
The variance in the speed of light due to the observer's motion.
What was the ether thought to be?
A substance that filled space and was essential for the propagation of light.
A form of dark matter that interacts with electromagnetic radiation.
A type of energy field that affects the speed of light.
What did the Michelson-Morley experiment first set out to find in 1881?
If the speed of light in the direction of Earth's motion through space differed from the speed of light in a perpendicular direction.
If the speed of light could be altered by magnetic fields.
If the speed of light could be increased with the help of the ether.
What was the purpose of the semi-silvered glass block in the Michelson-Morley experiment?
To detect absolute motion
To split the beam of monochromatic light into two beams
To measure the speed of light in free space
To prove the existence of the ether
What was the expected result if the speed of light depended on the Earth's velocity according to Michelson and Morley's calculations?
The interference pattern would remain constant
The interference pattern would shift by about 0.05 fringe
The interference pattern would shift by about 0.4 w of a fringe
The interference pattern would not be visible
What was the actual result of the Michelson-Morley experiment when the apparatus was rotated through 90 degrees?
A shift of 0.4 w of a fringe was detected
A shift of 0.05 fringe was detected
No shift was detected
The experiment was inconclusive
What conclusion did the Michelson-Morley experiment lead to regarding the ether?
The ether existed and affected the speed of light
The ether existed but did not affect the speed of light
The ether did not exist, and light travels without a material medium
The ether's existence could not be determined
Which theory explained the null result of the Michelson-Morley experiment regarding the speed of light?
General Theory of Relativity
Quantum Theory
Theory of Special Relativity
Classical Mechanics
