Physics paper 2 Flashcards
What is the amplitude of a wave
The amplitude ( ) of a wave is the distance from the centre line (or the still position) to the top of a crest or to the bottom of a trough
What is the wave length
The distance between two adjacent waves at the same point
What is frequency
The number of complete waves passing a certain point a second
frequency is measured in Hz
1Hz is 1 wave per second
When a wave arrives at a boundary what three things could happen
Absorbed
Transmitted
Reflected
What happens if a wave is absorbed by a material
The energy of the wave is transferred to the materials energy stores
What happens if the wave is transmitted through a material
The waves carries on travelling through the material which often leads to refraction
What happens if a wave is reflected by a material
The wave hits a boundary and changes direction
What is Refraction
Waves changing direction at a boundary after hitting the boundary at an angle
What happens if the wave slows down
It bends closer to the normal
What happens if a wave speeds up
It bends away from the normal
Since speed increases and frequency is unchanged, the wavelength must increase.
What is optical density
Is a measure of how quickly light can go through a material
The higher the optical density, the slower the light travels through the material
What are the qualities of transverse waves
Oscillations/vibrations are perpendicular (at 90 degrees) to the direction of energy transfer
What are the qualities of longitudinal waves
Oscillations are parallel to the direction of energy transfer
What type of wave are EM waves
Transverse
How do EM waves transfer energy
through vibrations of electric and magnetic fields
Why do EM waves have large ranges of frequencies
EM waves are generated by a variety of changes in atoms and their nuclei
What EM waves made up of
EM waves are made up of oscillating electric and magnetic charges
Why are Radio waves produced by AC current
AC are made up of oscillating charges. As the charges oscillate, they produce oscillating electric and magnetic fields i.e. radio waves/ EM waves
What is the object in which charges oscillate to produce radio waves called
A transmitter
Why can long radio waves be received even if they are not in the direct line of sight of the transmitter
Long radio waves diffract along the curvature of the Earth as well as around hills and other obstacles thus making it possible for them to be received
Why can short wave lengths be received from long distances
They are reflected off the ion sphere.
What is the disadvantage of TV and FM waves
They have very short wave lengths- So to get reception you must be in direct sight of the transmitter
What are the uses of microwaves
They are used in:
Satellites and microwaves
Why are microwaves used in satellites
Microwaves can easily pass through the Earths watery atmosphere
How are microwaves used in Microwave ovens
The microwaves are absorbed by the water molecules in the food- this then causes the water to heat up as it’s absorbed the energy of the microwave
The water molecules then transfer this energy to the rest of the molecules in the food by heating
What are the uses of infra-red radiation
it can be used to monitor temperature- The more warm an object the more infra-red radiation it emits
It can be used to heat objects up- the more infra red radiation an object absorbs the hotter it gets
How is visible light used to transmit data
Optical fibers carry data over long distances as pulses of lights
They work because light rays are bounced back and forth until they reach the end of the fibre
What is fluorescence
A property in which UV radiation is absorbed and visible light is emitted
How is UV radiation used
Sun beds
Fluorescent lights
Security pens
How are X-rays and Gamma rays used
X-rays images- X-rays easily pass through flesh but not so easily through denser materials such as bone or metal thus creating X-ray images
Radiotherapy- the use of gamma rays and x-rays to kill off cancer cells and treat people with cancer
A medical tracer- a gamma emitting source is injected into the patient- and its progress can be easily followed- gamma rays can easily pass through body and be detected
What are radiation doses measured in
Sieverts
1 sievert = 1000 milli sieverts
What factor determines what effect each type of radiation has on you
How much energy the wave transmits
Low frequency radio waves won’t cause much harm and easily pass through the body
High frequency waves such as UV, X-ray and gamma transmit a lot of energy thus causing a lot of damage in body
What factor determines what effect each type of radiation has on you
How much energy the wave transmits
Low frequency radio waves won’t cause much harm and easily pass through the body
High frequency waves such as UV, X-ray and gamma transmit a lot of energy thus causing a lot of damage in body
What happens to an objects as it cools down
(infrared radiation)
The object emits more infrared radiation than it absorbs as it cools down
What happens to an object as it heats up
(infrared radiation)
The object absorbs more infrared radiation than it emits as it warms up
What happens to objects that stay at a constant temperature (infrared radiation)
They absorb and emit infrared radiation at the same rate
What does the closeness of the lines in a magnetic field tell you about the magnetic field
It tells you the strength of the magnetic field
The closer the lines the stronger the magnetic field
Why do compass needles always point north
They always point north due to the fact that Earth generates its own magnetic field. This then shows that the core of the Earth must be magnetic
What are the two types of magnets
Permanent magnets and induced magnets
What are permanent magnets
Magnets that produce their own magnetic field
What are induced magnets
Magnetic materials that turn into magnets when they are in a magnetic field
The force between permanent and induced magnets is always
Attractive
What happens when a current flows through a wire (that is related to magnetic fields)
A magnetic field is produced around the wire
What happens when you change the direction of the current flowing through the wire (in relation to magnetic fields)
The direction of the magnetic field changes-Use right-hand thumb rule
What is the strength of the magnetic produced by a wire dependent on
The strength of the magnetic field is dependent on the amount of current flowing through the wire and how far away from the wire the magnetic field is
The larger the current or the closer the magnetic field is to the wire the stronger the magnetic field
How can you increase the strength of a magnetic field that is produced from a wire
You have to wrap the wire into a coil - the coil is then called a solenoid
What is a solenoid
A coil of wire
Why do solenoids have strong magnetic fields
A lot of field lines around each loop of the wire line up with each other. This leads to a lot of field lines pointing in the same direction that are very close to each other. Thus the closer the field lines the stronger the magnet
How can you increase the field strength of a solenoid
You can increase the strength of a solenoid even more by putting an iron rod at the center of the coil. Whenever the coil has current flowing through it the iron rod becomes an induced magnet
What is a solenoid with an iron core called
An electro magnet
In the Flemings left hand rule what does the first finger represent
The direction of the field
In the Flemings left hand rule what does the second finger represent
The direction of the current
In the Flemings left hand rule what does the thumb represent
The direction of the force/motion
What do vectors have
Vector quantities have direction and magnitude
What do scalars have
Scalar quantities only have magnitude
What are some examples of Vector quantities
Force, velocity, displacement, acceleration, momentum
What are some examples of scalar quantities
speed, distance, mass, temperature, time
What is a force
A force is a push or a pull on an object that is caused by it interacting with something
What is a contact force
A contact force is any force that occurs as a result of two objects making contact with each other.
What is a non-contact force
A non-contact force is a force that doesn’t need two objects touching each other to act
What is gravitational force
The force of attraction between masses
What are the two important effects that is caused by gravitational force
On the surface of the planet, it makes all things fall towards the ground
It gives everything a weight
What is weight
Weight is the force acting upon an object due to gravity
What is mass
The amount of stuff in an object
What does the weight of an object depend on
The gravitational field strength of a location
Is mass a force
No
What is the formula that links mass and weight
Weight= Mass X Gravitational field strength
What is a resultant force
The overall force on a point or object
What happens when a force moves an object through a distance
Energy is transferred and work is done
How do the force show if an object is at equilibrium
If the forces are balanced the the onject is at equlibrium
What is a change in a shape called
deformation
What may happen if you apply a force to an object
You may cause the object to stretch, compress or bend
How many forces would you need to physically deform an object
You would need more than one force as if you just applied one force to an object the object would move in the direction of the force and not get deformed
What is elastic deformation
Elastic deformation is when an object is able to return to its original shape after the force has been removed
What is inelastic deformation
Inelastic deformation is when an object doesn’t return to it’s original shape after the force has been removed
What is the extension of a stretched spring directly proportional to
The extension is directly proportional to force but this stops working if the force is great enough
What is the limit of proportionality
The maximum force before the force becomes too great and in no longer proportional to extension.
On force extension graphs this is seen as the start of a curve
What equipment do you need to investigate the link between force and extension
Clamp
Fixed ruled on clamp
a spring
a hanging mass
A weighted stand
What is the method to investigate the link between force and extension
measure natural length of spring with millimeter ruler clamped on stand at eye level. To make the reading more accurate add a market at end of spring
Add a mass to the spring and allow it to come to rest. Measure the mass and new length of spring. The extension is the length of new spring minus the length of the spring without any mass.
repeat last step with more masses added on each time until you have enough data
What is distance
How far an object has moved
Scalar quantity
What is displacement
it measure the distance and direction in a straight line from an objects starting point to it’s finishing point
What is speed
Speed is how fast your going
What is velocity
The speed of something in a given direction
What is the average speed of a person walking
1.5m/s
What is the average speed of running
3m/s
What is the average speed of cycling
6m/s
What is the average speed of a car
25m/s
What is the average speed of a train
55m/s
What is the average speed of a plane
250m/s
What is acceleration
Change in velocity in a certain amount of time
What does uniform acceleration mean
Constant acceleration
What is the acceleration due to gravity for all objects in free fall
9.8m/s squared- same value as gravitational field strength
What does the gradient show in distance-time graphs
speed- the steeper the graph the higher the speed
What do curves represent in distance-time graphs
Acceleration/ Deacceleration
A steepening curve means its speeding up
A leveling off curve means its slowing down
What does the gradient in a velocity-time graph represent
Acceleration
What doe flat sections in a velocity-time graph represent
travelling at a steady speed
What does the steepness of the graph tell you about the acceleration
The steeper the graph the greater the acceleration or deacceleration
What does a curve in a velocity time graph represent
changing acceleration
What does the area under the velocity-time graph represent
distance travelled
What is drag
The resistance you get in fluid (a gas or a liquid) this means that air resistance is a type of drag
What is air resistance
A type of drag where the frictional force is produced by the air acting on a moving object
What is the important factor in reducing drag
Making sure the shape of the object is streamlined
What typically happens to terminal velocity of an object if its less streamlined/ more surface area
The terminal velocity will lower
What happens if the resultant force of a stationary object is zero
The stationary object will stay still
What happens if the resultant force of a moving object is zero
The moving object will carry on moving at the same velocity, speed and direction
What is newtons first law of motion
an object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means:
a stationary object stays stationary
a moving object continues to move at the same velocity (at the same speed and in the same direction)
What is the formula that describe newtons second law of motion
Force = Mass X Acceleration
What is inertia
The tendency to continue in the same state of motion is called inertia.
What is Newtons third law
When two objects interact the forces they exert upon each other are equal and opposite
What is thinking distance
how far the car travels during the drivers reaction times
What is the braking distance
The distance taken to stop under the force applied by the brakes
What factors affect thinking distance
the speed you are travelling at- faster your going the further you go during time you take to react
your reaction time
What factors affect stopping distance
The speed your travelling at- the faster your travelling the longer it takes to stop
The weather or road surface- if the road is icy or wet (reduces friction)
The condition of tires- if the tyres of the vehicle don’t have a tread left then they cannot get rid of water in wet conditions. Which leads to them skidding
How good your brakes are- if brake or worn or faulty wont be able to appl as much force.
What happens to the momentum before and after an event in a closed system
In a closed system the total momentum before an event is the same as after an event. This is called the conservation of mass
What is a method to investigate how force affect acceleration
Set up a trolley so it holds a piece of card with a gap in the middle that will interrupt the signal of the light gate twice. Measure the length of each bit of the card that will pass through the light gate and in put this into the software. The light gate can use this to measure the velocity of each bit of card it can then use this information to to figure out the acceleration of the trolley
Connect the trolley to a string that goes over a pulley to a hook that you know the mass of and you can easily add more weights to you
The weight of the hook and any masses accelerates both the trolley and the masses so you are investigating the acceleration of the system (the trolley and the masses together)
Mark a starting line on the table the trolley is on, so the trolley always travels the same distance to the light gate
Place the trolley on the starting line while making sure the string is taught by letting the hook and masses hang. Then let go.
Record the acceleration measured by the light gate and repeat the last step so you can calculate an average acceleration
What is a method to investigate how mass affect acceleration
Set up a trolley so it holds a piece of card with a gap in the middle that will interrupt the signal of the light gate twice. Measure the length of each bit of the card that will pass through the light gate and in put this into the software. The light gate can use this to measure the velocity of each bit of card it can then use this information to to figure out the acceleration of the trolley
Connect the trolley to a string that goes over a pulley to a hook that you know the mass of and you can easily add more weights to it
Then to investigate the mass you progressively add more masses to the trolley each time you repeat the experiment
Don’t add masses to the hook as that would just increase the force
Then draw a starting line on the flat surface where you are doing the experiment to make sure the trolley always travels the same distance
Make sure the string is taught and then let go
Record the acceleration measured by the light gate and repeat the experiment so you can get an average acceleration
Then do the experiment again but with more mass on the trolley and repeat until you have the average acceleration of the trolley with all your masses.
What is the wave length of radio waves
1m- 10 to the power of 4 m
What is the wave length of micro waves
10 to the power of -2 meters
What is the wave length of infra red waves
10 to the power of -5 meters
What is the wave length of visible light
10 to the -7 meters
What is the wave length of ultra violet light
10 to the -8 meters
What is the wave length of X-rays
10 to the -10 meters
What is the wave length of gamma rays
10 to the -15 meters
