Studied by 0 PeopleTags & Description
Protons natural effect on each other is that they
repel each other
A proton's quark configuration is
Up, Up, Down (uud)
The charge of a proton is positive because
The sum of its quark's charges = 1 u = +2/3 d = -1/3 Configuration = uud = 2/3 + 2/3 - 1/3 = 3/3 = 1
The charge of a pion is positive because
The sum of its quark's charges = 1 u = +2/3 d^-(anti-down quark) = 1/3 Configuration = ud^- = 2/3 + 1/3 = 3/3 = 1
The charge of a neutron is neutral because
The sum of its quark's charges = 0 u = +2/3 d = -1/3 Configuration = udd = 2/3 - 1/3 - 1/3 = 0/3 = 0
An atom contains
a positively charged nucleus composed of protons and neutrons.
electrons that surround the nucleus
A nucleon is
a proton or neutron in the nucleus
Each electron has
a negative charge
The electrons are held in the atom by
the electrostatic force of attraction between the negatively charged electrons and the nucleus, due to the protons giving the nucleus a positive charge
The nucleus is ? times the size of the atom
0.00001 (one ten thousandth)
The charge of a particle is shown in
Coulombs (C)
The mass of a particle is measured in
Kilograms (kg)
An electron has ? compared to a proton
much less mass
opposite charge
A similarity between protons and neutrons is
their almost equal mass
Neutrons are
uncharged
An electron has a mass ? times smaller than a proton
2000
Atoms of the same ? (with the same number of ?) that have different numbers of ? are called ?
Atoms of the same element (with the same number of protons) that have different numbers of neutrons are called isotopes
Isotopes are
atoms with the same number of protons and a different number of neutrons
The total number of protons and neutrons in an atom is called
the nucleon number / mass number
Each type of nucleus is called
a nuclide
The specific charge of a charged particle =
charge / mass
A stable isotope has ? that do not ? so there must be ?. We call this the ? because it overcomes the ? between ?, keeping them together.
A stable isotope has nuclei that do not disintegrate so there must be a force holding them together. We call this the strong nuclear force because it overcomes the electrostatic force of repulsion between protons and neutrons, keeping them together.
10^-15 =
femto - fm
The electrostatic force between two charged particles has ? range but ?
The electrostatic force between two charged particles has infinite range but the force decreases as the range increases
The strong force is (range)
Attractive from 4fm to 0.5fm Closer than 0.5fm it becomes repulsive
In Young's double slit experiment:
d is ?
s is ?
Theta is ?
D is?
w is ?
d is gap separation
s is also gap separation
Theta is the angle from n = 0 to n = x
D is the distance from the gaps to the screen
w is the fringe spacing
What's the name given to a maximum on a standing wave
An antinode
For the first harmonic, in terms of length: wavelength =
2 L
The nth harmonic has length L given by
L = (n/2)wavelength
Points either side of the rest position in a standing wave are ?(phase)
180 degrees out of phase / antiphase
Points on the same side of the equilibrium position on a stationary wave are?(phase)
In phase
A progressive wave is
a wave that moves through the medium
When two waves meet they
Superpose
The frequency of the nth harmonic is given by
n * fundamental frequency
If the frequency of the first harmonic is 20Hz, the third has f =
60Hz
When labeling standing waves, antinodes are labeled ? and nodes are labeled ?
Antinodes : A
Nodes : N
Longitudinal waves differ from transverse in that
points on the wave oscillate in line with the direction the wave travels.
Two points on a progressive wave are one-eighth of a wavelength apart. The distance between them is 0.5 m, and the frequency of the oscillation is 10 Hz. What is the minimum speed of the wave?
40 m/s
Because if λ / 8 = 0.5 λ= 4 v = fλ v = 10 * 4 = 40 m/s
The speed of sound in water is 1500 m s−1. For a sound wave in water having frequency 2500 Hz, what is the minimum distance between two points at which the vibrations are 𝜋/3 rad out of phase?
0.1 m
v = fλ v / f = λ 1500 / 2500 = λ = 0.6 m λ = 2𝜋 𝜋/3 = λ/6 𝜋/3 = 0.6 / 6 = 0.1 m
A source emits light of wavelength 600 nm as a train of waves lasting 0.01 μs. How many complete waves are sent out? speed of light = 3 × 108 m/s
5 * 10^6
v = fλ v / λ = f (3 * 10^8) / (600 * 10^-9) = f = 5 * 10^14 If a clock ticks once a seconds then to find the number of ticks every half a second: 1 * 1/2 = 1/2 ticks per second
So (5 * 10^14) * (0.01 * 10^-6) = number of waves = 5 * 10^6
A progressive wave in a stretched string has a speed of 20 m s−1 and a frequency of 100Hz. What is the phase difference between two points 25 mm apart?
v = fλ v / f = λ 20 / 100 = λ = 0.2 m 25 * 10^-3 = 0.025 m 0.2 / 0.025 = 8 So the phase difference is an eight of a wavelength or 2pi/8 = pi/4 radians
Monochromatic light passes from air into water. The ? change but not the ?
The velocity and wavelength change but not the frequency
The least distance between two points of a progressive transverse wave which have a phase difference of 𝜋3 rad is 0.050 m. If the frequency of the wave is 500 Hz, what is the speed of the wave?
150 m/s
pi / 3 = 0.05 m 2pi = λ pi = 0.15 2pi = 0.3 = λ v = fλ v = 500 * 0.3 = 150 m/s
State the characteristic features of longitudinal waves
particle vibration (or disturbance or oscillation) (1) same as (or parallel to) direction of propagation (or energy transfer) (1)
State the characteristic features of transverse waves
(particle vibration) perpendicular to direction of propagation (or energy transfer) (1)
Explain how energy is transmitted in a sound wave.
particles in the transmitting medium are made to vibrate/given energy
or mention of a compression/region of increased pressure (or rarefaction) cause nearby particles to vibrate/have energy/move
or the compression produces a compression further along (the medium)
2
Define the amplitude of a wave.
maximum displacement from equilibrium/mean position/mid-point/etc (1)
Give examples of transverse waves
electromagnetic radiation (1) surface of water/water waves/in ripple tank (1) rope (1) slinky clearly qualified as transverse (1) secondary ('s') waves (1)
Differences between transverse and longitudinal waves
transverse wave: oscillation (of medium) is perpendicular to wave travel or transverse can be polarised or all longitudinal require a medium
Explain what is meant by the frequency of a wave.
number of (complete) waves (passing a point) in 1 second OR number of waves / time (for the waves to pass a point) OR (complete number of) oscillations \ vibrations per second OR 1 / T with T defined as time for 1 (complete) oscillation
A continuous ultrasound wave of constant frequency is reflected from a solid surface and returns in the direction it came from. Assuming there is no significant loss in amplitude upon reflection, describe and explain the effect the waves have on the particles in the medium between the transmitter and the solid surface.
• mention of nodes and antinodes • particles not moving at a node • maximum displacement at antinode • particles either side of node in antiphase / between two nodes in phase • variation of amplitude between node
Any process of creating ions is called
ionisation
?, ? and ? create ions when they pass through atoms
Alpha, beta and gamma radiation
? passing through a ? tube create ions with they collide with vapour in the tube
Electrons passing through a fluorescent tube create ions with they collide with vapour in the tube
An electron that moves through a potential difference of 2000V is ?eV
2000eV
An ion of charge +2e moves though a potential difference of 10V is ?eV
20
Atoms can absorb energy from colliding electrons without being ionized via
excitation
The energy values at which an atom absorbs energy are its
excitation energies
The lowest energy of an atom is called its
ground state
Excitation energy measurements are used to construct
an energy level diagram for the atom
When electrons move down an energy level a ? which is called ?
When electrons move down an energy level a photon is emitted which is called de-excitation
Acceleration of free fall is
The acceleration of an object acted on only by the force of gravity
Alpha radiation is
Particles that consist of two protons and two neutrons
A point on a stationary wave moves
up and down either side of the rest position / equilibrium position
Two points on a stationary wave, one either side of the rest position, have the phase relationship:
180 degrees out of phase
Two points on a stationary wave that are the same side of the rest position are
in phase
Halfway between two nodes is a
antinode
On a stationary wave, if L is 0.48m what is the wavelength?
0.96m wavelength = twice the distance between two nodes / antinodes where L is the distance between two nodes / antinodes
Stationary waves: Equation to find frequency of nth harmonic
f = (n * c) / 2L
A guitarist wants to increase the fundamental frequency of his strings, how might he do it?
Increase the tension
Define: fundamental frequency
the frequency of the first harmonic
frequency is
the number of full wave cycles per second
in longitudinal wave, points on the wave
oscillate in the axis of the wave's direction of travel
Total internal reflection occurs when
the angle of incidence is greater than the critical angle
equation for a wave passing between two materials, involving their refractive index and angles
n1 * sinANGLE1 = n2 * sinANGLE2
The critical angle is found using the equation:
n1 * sinANGLEc = n2 * sin90 Where ANGLEc is the critical angle, being reflected 90 degrees
An emitted photon has energy 9.92 * 10-19 J Calculate its wavelength
frequency = E / h wavelength = c / f so wavelength = c / E / h wavelength = ch / E wavelength = ((3 * 10^8) * (6.63 * 10^-34))/(9.92 * 10^-19) wavelength =
An electron with no excess energy is in ? state An electron with some excess energy is in ? state An electron with enough excess energy to leave an atom is in ? state
An electron with no excess energy is in its ground state (n = 1) An electron with some excess energy is in an excited state An electron with enough excess energy to leave an atom is in an excited state (n = infinite)
Work function equation
Intensity of light is
the number of photons striking a surface per second
What is the work function equal to?
the minimum energy required for an electron to be removed from a cold atom with 0 kinetic energy
In the work function what is Ek?
The maximum amount of kinetic energy has after escaping an atom
What kind of experiment would confirm that electrons have wave-like nature?
diffraction (through an atomic lattice)
why is it easier to demonstrate the wave properties of electrons than protons?
because electrons have less mass, so larger wavelengths