Physics :)

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

Equation relating wavelength, plank's constant and momentum:

p \= h / wavelength

Kinetic energy \=

1/2mv^2

Equation relating wavelength, plank's constant,

E \= hf

Refractive index equation given speeds

n1 \= (c / c1)
n1 \= refractive index in material 1
c \= speed of light in vacuum
c1 \= speed of light in material 1

A wavelength in radians \=

2pi

The equation for diffraction grating experiments

n * wavelength \= d sinX
d is separation of gaps
x is angle f diffraction
n is the order number

State what is meant by the specific charge of a nucleus and give an
appropriate unit for this quantity.

the ratio of charge to mass of nucleus
C /kg

Nucleus X has the same nucleon number as nucleus Y. The specific charge of
X is 1.25 times greater than that of Y.
Explain, in terms of protons and neutrons, why the specific charge of X
is greater than that of Y.

total number of protons and neutrons the same but more protons therefore greater charge

Describe how the strong nuclear force between two nucleons varies with the separation of the nucleons quoting suitable values for separation.

repulsive then attractive(1)
short range(1)

An unstable nucleus can decay by the emission of an alpha particle.
State the nature of an alpha particle.

a helium nucleus

State what is meant by isotopes.

same atomic number/proton number (1)

different number of neutrons/nucleons (1)

A stable atom contains 28 nucleons.
Write down a possible number of protons, neutrons and electrons contained in the atom.

number of protons \= number of electrons (1)

number of protons + number of neutrons \= 28 (1)

Describe how the strong nuclear force between two nucleons varies with the separation of the nucleons, quoting suitable values for separation.

repulsive below / at 0.5 fm (accept any value less or equal to 1 fm) ✓
attractive up to / at 3 fm (accept any value between 0.5 and 10 fm) ✓
short range OR becomes zero

State the combination of quarks that makes up a neutron.

d + d + u

State the products arising from the decay of an anti-down quark

anti up-quark plus positron plus electron neutrino

Name the class of particles of which the proton is a member.

baryon / hadron