Physics Flashcards
What are the 6 base quantities, their unit and their symbol and it’s unit
Mass, m, Kilogram, kg
Time, t, Second, s
Length, l, Metre, m
Current, I(i), Ampere(Amps), A
Temperature, T, Kelvin, k
Amount of Substance, N/A, Mole, mol
What are the 10 multiples and submultiples we use at A-Level their symbol and their multiplying factor
femto, f, x10-15
pico, p, x10-12
nano, n, x10-9
micro, u with double tail, x10-6
milli, m, x10-3
centi, c, x10-2
kilo, k, 1x10+3
Mega, M, x10+6
Giga, G, x10+9
Tera, T, x10+12
Name 6 vectors
Displacement
Velocity
Acceleration
Force
Current
Momentum
Name 10 Scalors
Distance
Speed
Rate of change of speed
Time
Charge
Kinetic energy
Temperature
Area
Volume
Mass
What’s the difference between a scalar and a vector.
A scalar is a physical quantity that has magnitude and a unit however A vector is a physical quantity with magnitude, a unit and a direction.
When adding vectors which way is positive and which way is negative.
Right is positive
Left is negative
How do you find the resultant vector
Nose to tail method.
How do you resolve a vector
For vertical component we use resultant vector x sin(angle)
For horizontal component we use resultant vector cos(angle)
What is the formula for force
F= mass x gravity (9.81)
What are the two formulas for moments
M= force x distance
(Nm= N x m)
F1xD1= F2xD2
What is the moment of a force about a pivot
The product of the force and the perpendicular distance from the pivot to the force.
What is Newton’s 2nd law
The acceleration of an object is inversely proportional to its mass but directly proportional to the resultant force on it.
What is the formula for Newton’s 2nd law
Force = mass x acceleration
What is the formula for resivitivity
P(resivitivity) = resistance x cross sectional area, per unit length
What is resivitivity
It’s the property of the material and is unique to each material
What is resistance
The opposition to the flow of electrons
What are 2 key facts about resistance
It is directly proportional to length but inversely proportional to the cross sectional area
What’s the formula for the volume of a cylinder.
V= (pi) radius(squared) x height or Length
Name the 5 SUVAT Equations
v=u+at
v2=u2+2as
s=ut+1/2at2
s=vt-1/2at2
s=1/2(u+v)t
What does SUVAT mean
v=final velocity
u=intial velocity
s=displacement
a=acceleration
t=time
What shape does an I-V graph take for a thermistor
A reverse teapot (short and stout)
What is Ohm’s law
Voltage is directly proportional to current as long as the temperature is constant in a metallic conductor.
What is the formula for Ohm’s law
Voltage = Resistance x Current
What are the 3 main equations to help with linear motion
Speed=distance/time
Velocity=displacement/time
Acceleration=velocity/time
How do you work out the acceleration from a velocity - time graph
Find the gradient of the line
How do you work out the velocity from a displacement - time graph
Find the gradient of the line.
What is the formula for internal res
EMF = Current x (load res + internal res)
EMF/Current = (load res + internal res)
Total res - Load res = internal res
What is the formula for range
Constant horizontal velocity x time of flight
What do waves do
Transfer energy from one position to another
What 2 groups can waves be classified as
Transverse and longitudinal
What direction do transverse wave oscillations go
Oscillations are perpindicular to wave direction
What direction do longitudinal wave oscillations go
Oscillations are parallel to wave direction
What are some examples of transverse waves
All EM waves, waves on a string, ripples on water and some shock waves
What are some examples of longitudinal waves
Sound waves (including ultrasound) and some shock waves.
What is the amplitude of a wave on a graph
The distance from the middle line to the top of the peak
What is the wavelength (lambda)(λ)/the time of a wave on a graph
The distance from the first peak to the 2nd peak
On a displacement - distance graph what dooes the amplitude tell us
The max displacement of particles measured in metres
On a displacement - distance graph what dooes the wavelength tell us
The distance travelled by the wave in one complete oscillation measured in metres
On a displacement - time graph what dooes the amplitude tell us
The max displacement of particles mesured in metres
On a displacement - time graph what dooes the peridoic time tell us
Time taken for the wave to complete one full oscillation measured in secs
What is the frequency of a wave
The no of oscillations in one sec or the amount of waves passing any point in one sec measured in hertz
What is the frequency equation
F=1/T
What is the wave speed equation
V= f x λ
What are mechanical waves
Waves that are produced by a disturbance such as a vibrating body in a material medium, whose particles are set into oscillation. E.g. Water waves need water.
What are electromagnetic waves
Waves that consist of a varying electric and magnetic field coupled together at 90 degrees to the wave direction: they dont require a medium to travel in and in fact find it easier to travel through a vacuum.
In a longitudinal wave where is the crest.
In the rarefaction.
In a longitudinal wave where is the trough.
In a compression.
What is the em spectrum
A continuum of radiation
What are the 7 regions of the em spectrum, there wave length and frequency
Gamma - 10^-12, ≤3x10^19 hz
X ray - 10^-10, 3x10^18 hz
Ultra Violet - 10^-8, 3x10^16 hz
Visible (red 700nm - violet 400nm), 6x10^14 hz
Infra Red - 10^-4, 3x10^12 hz
Micro - 10^-2, 3x10^10 hz
Radio - 1, 3x10^8 hz
What are the dangers of each em wave
Gamma - damages cell DNA and can cause cancer
X ray - damages cell DNA and can cause cancer
Ultra Violet - damages skin cells, disrupts DNA and can cause skin cancer
Visible (red - violet) - snow blindness (when the eye’s cornea becomes temporarily sunburned)
Infra Red - causes burns
Micro - can cause eye cataracts
Radio - heat up internal body tissue and can cause burns
What are the common uses of each em wave
Gamma - Killing cancer cells
X ray - Medical images of bones
Ultra Violet - Detecting forged bank notes, finding blood splatters
Visible (red - violet) - the only part we can see, used for photography, and optical fibres
Infra Red - heating, night vision equipment, tv remotes
Micro - Cooking, mobile phones
Radio - Television signals
How can you find the frequency of a wave
Frequency = speed of light (3x10^8)/λ (wavelength)
What is an example of polarisation.
Sunglasses
What type of waves can be polarised
Transverse
What is polarisation
Vibrations are only allowed in one plane only.
What 2 theories of light existed in the 17th century.
Corpuscular theory and huygens wave theory
What does the corpuscular theory think about light
It considders light to consist of streams of very tiny particles called corpuscles which move at very high speed in straight lines.
What does the corpuscular theory explain
Rectilinear propagation, reflection and refraction.
What does the huygens wave theory think about light
It proposed a wave theory for light in which the energy was emitted in a continuous stream from the source.
What does the huygens wave theory explain
Many physical optics phenomena (experiments in which measurements close to the wavelength of light are made)
Who came up with a new theory in 1864
Maxwell
What did maxwell suggest
He suggested light to be an em wave consisting of fluctuating electric and magnetic fields both coupled together at 90 degrees to each other and both at 90 degrees to the ray direction.
What is a polaroid
This is a manmade material used to produce polarised light.
What is c
The speed of light
What is the exact number of c
3x10^8
What are the classical equations for doppler shift
Observed frequency = (velocity of waves / velocity of waves + velocity of source) x emitted frequency
Observed wavelength = (1 + velocity of source / velocity of waves) x emitted wavelength
What scenario are we looking at the doppler shift from
Waves recieved by a stationary observer from a moving source
What is the difference between cosmological red shift and doppler red shift
in doppler shift, the only thing that matters is the relative velocity of the emitting object when the light is emitted compared to that of the receiving object when the light is received. In cosmological redshift, however, the emitting object is expanding along with the rest of the universe, and if the rate of expansion changes between the time the light is emitted and the time it is received, that will affect the received wavelength.
What is the equation for the red shift parameter of a receding galaxy
Z = the difference between the observed and emitted frequencies / emitted frequencies or the difference between the observed and emitted wavelengths/ emitted wavelengths
How can you find the recession speed of a galaxy
V = redshift parameter x speed of light (3x10^8)
What is hubbles law equation
Recessional velocity = hubbles constant (paramter, approx. 2.4x10^-18 s^-1) x distance between earth and galaxy in question.
How can you estimate the age of the universe
Time from big bang (Hubble time) = 1 / hubbles constant
What is the current estimate for the age of the universe
13.2 billion years
What is momentum
The product of an objects mass and its velocity
What is the momentum equation
Momentum = mass x velocity
Measured in kgms^-1 (Ns)
What is the principle of the Conservation of momentum for bodies in a collision
Provided no external forces are acting, the total momentum of a system of colliding bodies is constant.
What is the equation for momentum in a collision
Total momentum before collision = total momentum after collision
What is the difference between elastic and inelastic collisions
Elastic collisions are those in which energy is covered.
Inelastic collisions are those in which energy is not conserved.
What is impulse
Force time (Ns)
What is the equation for impulse
Ft (impulse) = m x change in velocity (delta v)
What is newtons 2nd law in terms of momentum
The change in momentum is directly proportional to the resultant force acting on it. Both act in the same direction.
What is the definition of energy
the stored ability to do work
What is the definition of work done
A constant force as the product of the force and the distance moved in the direction of the force.
What’s the work done equation
W = constant force x displacement
What is a joule
The amount of work done (or energy transferred) when a force of 1N moves through a distance of 1m.
What are the potential and kinetic energy equations
P.E. = mgh
K.E. = 1/2 mv^2
What is the principle of Conservation of energy
Energy cant be created or destroyed but can be changed from one form to another.
How can you calculate speed exchanges from kinetic energy to potential energy
V = the square root of u^2 - 2xgxh
How can you find the costant forve of an object
Wd = constant force x displacement so constant force = Wd / displacement
Or
(1/2 mass x v^2 - 1/2 mass x u^2) / displacement = constant force
What are the 2 power equations
P = wd / time
P = force / constant speed
What is the efficiency equation
Useful energy or power output / total energy or power input
What is energy conservation
The act of reducing energy consumption
What is energy efficiency
Any product or process that makes it possible to enjoy the same standard of living while using less energy.
What is energy efficiency
Any product or process that makes it possible to enjoy the same standard of living while using less energy.
Why is energy efficiency important to society
It reduces the strain that energy production puts on earth’s natural resources
Why is energy conservation important to society
Energy conservation has environmental benefits. Most of our energy resources will eventually be exhausted. Taking steps to reduce the consumption of our energy resources will, in turn, reduce the amount of pollution produced.
What is tir
A phenomenon that may occur as light attempts to move from a denser material e.g. glass to a less dense material such as water or air. This can only happen if light is increased beyond the value of the critical angle.
What is the snell’s law equation
Sin x angle of incidence / sin x angle of refraction
What is snell’s law used to find
The refractive index and an indication of the optical density
