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62 Cards in this Set
- Front
- Back
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What are electromagnetic waves ? |
Electromagnetic waves are transverse waves that all travel at the speed of light in air or vacuum |
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What type of electromagnetic waves can humans see ? |
Visible light |
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What is the order of the electromagnetic spectrum ? |
Radio waves Microwaves Infared waves Visible light Ultraviolet rays X rays Gamma rays |
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What is refraction ? |
When a wave passes through one medium into another it can be refracted and change direction |
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What are can change the direction the refraction happens ? |
The angle at which the wave hits the boundary Materials involved |
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What happens when the light travels from a low refractive index into a higher refractive index ? |
The light bends towards the normal path |
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What happens when a light tracked from a high refractive index to a low refractive index ? |
The light bends away from the normal |
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Why does refraction happen ? |
Because the wave speed in the different media’s is different |
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What are radio used for and why ? |
Television and radio because they are low energy waves therefore not harmful which makes them ideal |
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What are microwaves used for ? |
Satellite communication because they travel in straight lines through the atmosphere making them ideal for transmitting signals |
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What are x rays used for ? |
Medical imaging and treatments as xrays are able to penetrate soft tissue but not bone |
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What are gamma rays used for ? |
Sterilising food and treatment as gamma rays are the most energetic of all electromagnetic waves and can be used to destroy bacteria and tumours |
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What is meant by the term oscillate |
To vibrate /swing side to side with a regular frequency |
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How are radio waves made in electrical circuits |
Through oscillations that allow messages to travel in waves Then radio waves are absorbed by a conductor that then creates a the same frequency as the radio wave |
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What affects does electrons mining between energy levels result in ? |
Electron moving between energy levels because of heat or electrical excitation can generate waves e.g infared waves visible light ultraviolet and x rays |
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What happens when the nucleus of an atom changes ? |
The atom can generate waves as a result of an unstable nucleus that give out excess energy as gamma rays |
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What are the risks of ultraviolet waves to a human ? |
Ultraviolet waves can cause the skin to age prematurely and increase the risk of skin cancer |
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What type of radiation is xrays and gamma rays ? |
Ionising radiation which can damage cells by ionising atoms and if absorbed by the nucleus of the cell ,can cause mutations and cancer |
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What direction of oscillation is in transverse waves ? |
Perpendicular at right angles to the direction in energy transfer |
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What is the oscillations in longitudinal waves ? |
The oscillations are parallel to the direction of energy transfer Shown through slinky compressing and expanding side to side ————— |
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What is the frequency of a waves ? |
The number of waves passing through a fixed point per second measured in hertz (hz) |
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What is the amplitude of the wave ? |
The maximum length away from the middle line of the wave |
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What is the wavelength? |
The distance from one point on a wave to the equivalent point on the next wave in metres |
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What is a period of a wave ? |
The time taken for one complete oscillation in seconds |
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What is the crest of a wave ? |
The top of the wave |
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What is the trough ? |
The bottom of a wave |
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How do you measure the period of a wave |
1 / frequency |
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Equation for wave speed ? |
Frequency x wavelength |
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What is a contact force ? |
A force where the two objects are touching e.g the tension as two people pull against one another |
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What can work be described as ? |
When a force causes an object to move ,work is done on the object This is because it takes energy to move the object
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What is a non contact force ? |
Where the two objects aren’t touching e.g the force of gravity acts even when the objects aren’t touching |
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What is the difference between scalar and vector quantities ? |
Scalar quantities have a magnitude (size ) e.g number of apples Vector quantities has magnitude and direction e.g velocity which shows the speed and direction of travel
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What quantity are forces ? |
Vector quantities |
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Examples of contact forces |
Friction Air resistance/drag Tension Normal contact force Upthrust |
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Examples of non contact forces |
Gravitational force Electrostatic force Magnetic force |
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What is weight |
Weight is the force acting on an object due to gravity The weight of an object depends on the gravitational field strength where the object is and is directly proportional to its mass |
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Equation for weight |
Weight = mass x gravitational field strength |
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What is a resultant force ? |
When more than one force acts on an object , these forces can be seen as a single force that has the same effect as all the forces acting together |
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Equation for work done |
Force x distance (moved along the line of action of the force ) |
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How many forces does it take to change the shape of an object ? |
More than one force must be applied e.g spring must be pulled from each end to stretch it |
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What is Newton’s first law ? |
An object will remain in the same state of motion unless acted on by an external force |
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If an object is returns it it’s original state after the forces are removed what’s it called ? |
Elastically deformed |
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If an object does not return to its original state it has been ... |
Inelastically deformed |
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What is the extension of an elastic object directly proportional to ? |
The applied force however once the limit of proportionality has been exceeded: Doubling the force will no longer exactly double the extension Relationships become non linear A force extension graph will stop being straight |
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What does it mean if the spring constant is higher ? |
The spring is stiffer |
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Equation for force on a spring ? |
Spring constant x extension |
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What is distance ? |
Distance is a scalar quantity It is how far an object moves and doesn’t take in account which direction it’s going |
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What is displacement? |
Displacement is a vector quantity as it has a magnitude and a direction |
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What is the equation for distance ? |
Speed x time |
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What is velocity ? |
The speed of an object in a given direction |
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What is acceleration ? |
The acceleration of an object is a measure of how quickly it speeds up slows down or changes direction |
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What is the equation for acceleration? |
Change in velocity / time taken |
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What is Newton’s third law ? |
For every action there is an equal and opposite reaction |
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What is the equation for momentum ? |
Momentum = mass x velocity |
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What is momentum |
Momentum is the movement of objects Greater the momentum the more force needed to stop it At the same speed , a large mass will have more momentum than a small mass |
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Before and after an event momentum is ... |
Equal |
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What two things effect the stopping distance of a car ? |
Thinking distance (drivers reaction time ) Braking distance (distance travelled under braking force )- depends on speed going |
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Factors effecting reaction time : |
Normal reaction time 0.4-0.9 seconds Tiredness ,drugs and alcohol Distractions e.g mobile phones |
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Factors effecting breaking distance : |
Condition of the road - if wet less friction Vehicle condition - worn brakes or tyres Speed car is travelling at - higher speed further the stopping distance |
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Equation for braking force required |
Work done (kinetic energy ) = force x braking distance |
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What is the motor effect ? |
When a current carrying conductor is placed in a magnetic field , it creates a force even though the conductor isn’t magnetic |
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Two characteristics of electrons |
Electron spin creating weak magnetic field Negative charge |
