Section 4 - Properties Of Waves Flashcards by Matthew Gudge

What is a wave?

Wave transfers energy in the direction of travel

How well did you know this?

Not at all

Perfectly

What is the equation for wave speed?

V=f x wavelength

How well did you know this?

Not at all

Perfectly

Describe a transverse wave?

A wave that vibrates perpendicular to the direction of travel

How well did you know this?

Not at all

Perfectly

What are some examples of transverse waves?

All light and electromagnetic radiation

How well did you know this?

Not at all

Perfectly

What is amplitude?

The maximum displacement of a point on a wave from into undisturbed position

How well did you know this?

Not at all

Perfectly

What is wavelength?

The distance between the same point on two adjacent waves

How well did you know this?

Not at all

Perfectly

What is frequency?

The number of complete waves that pass a certain point per second

How well did you know this?

Not at all

Perfectly

Describe a longitudinal wave

A wave that vibrates parallel to the direction of travel

How well did you know this?

Not at all

Perfectly

What is an example of a longitudinal wave?

Sound waves

How well did you know this?

Not at all

Perfectly

What is wave speed?

Is the speed at which energy is being transferred

How well did you know this?

Not at all

Perfectly

What is reflection?

Reflection is when a wave bounces off a surface

How well did you know this?

Not at all

Perfectly

What is the law of reflection?

The law of reflection states that the angle of incidence always equals the angle of reflection

How well did you know this?

Not at all

Perfectly

How can reflection be shown using water waves

In a ripple tank a dipper will create waves, when a barrier is places the waves will be reflected

How well did you know this?

Not at all

Perfectly

What are the two shoes of reflection and explain them

Diffuse - when the light hits a bumpy surface and the image is unclear
Spectral - when the light hits a flat surface and the image is clear

How well did you know this?

Not at all

Perfectly

What is refraction?

When waves change direction when passing from one medium to another

How well did you know this?

Not at all

Perfectly

Why do waves travel differently in different mediums?

Due to different densities the way will slow down or speed up

How well did you know this?

Not at all

Perfectly

What happens when a wave enters a more dense medium?

The wave slows down and bends towards the normal

How well did you know this?

Not at all

Perfectly

What happens when a wave enters a less dense medium?

The wave speeds up and bends away from the normal

How well did you know this?

Not at all

Perfectly

What happens to wavelength and frequency during refraction.

Wave speed changes and therefore wavelength or frequency must change
Frequency never changes so wavelength must always change

How well did you know this?

Not at all

Perfectly

What is dispersion?

Dispersion is when white light spreads out into 7 different colours - a rainbow
This is because he different wavelength inside of visible light refract by different amounts

How well did you know this?

Not at all

Perfectly

What is refractive index?

The ratio of the speed of a wave in two different regions

How well did you know this?

Not at all

Perfectly

What is the refractive index of a vacuum?

How well did you know this?

Not at all

Perfectly

What is the equation for refractive index?

Refractive index = speed of light in vacuum / speed of light in material

How well did you know this?

Not at all

Perfectly

What is snells law?

It links the equation for refractive index to the angle of incidence and refraction

How well did you know this?

Not at all

Perfectly

What is snells equation?

Refractive index = sin(i) / sin(r)

What is total internal reflection?

When no refraction occurs and the light is reflected back into the denser medium

What are the two criteria for total internal reflection?

The rays of light must be going from a more dense to a less dense medium The angle of incidence must be greater than the critical angle

What is the critical angle?

The angle of incidence when the ray refracts at a 90 degree angle

What id the formula for a critical angle?

SinC = 1/n. Or. Sin critical angle = 1 / refractive index

How do converging lenses work?

Convex lenses that refract the light inwards to a single point

How do diverging lenses work?

In concave lenses the light is refracted outwards and is dispersed

Explain where the principal focus will form.

On convex lenses - where the rays meet On concave lenses - where the rays image meet behind lens There is a principal focus on both sides, equal distance from the middle

What is the name of the distance between the principal focus and the centre of the lens?

The focal length - shorter the length the more powerful the lens

What is the difference between a real and virtual image?

A real image is when the light ray come together whereas a virtual image is when they don’t come together where the image appears

How would you describe a real image?

Inverted Real Smaller

How would you describe a virtual image?

Virtual Upright Smaller

What image will a contact lenses make on a ray diagram?

A virtual image on the same side of the lens as the object

In a convex lens what would happen to the image at different focal lengths?

Over 2F - smaller, inverted, real At 2F - same size, inverted, real Over 1F - larger, inverted, real Under 1F - larger, upright, virtual

What is the order of the electromagnetic spectrum starting with the smallest?

Gamma rays X rays Ultra violet Visible light Infared Micro waves Radio waves

What is used to describe visible light of a single frequency?

Monochromatic

What are some typical uses of radio waves?

Radio and television

What are some typical uses of microwaves?

Mobile phones, microwave ovens

What are some typical uses of infared?

ELectrical grills, thermal imaging, optical fibres

What are some typical uses of visible light?

Photography and vision

What’s re some typical uses of ultraviolet?

Detecting fake items, sterilising water

What are some typical uses to X-rays?

Medical scanning, security scanning

What are some typical uses of gamma rays?

Sterilising food and medical equipment , treating cancer

What is the speed of electromagnetic waves in a vacuum?

3.0 x 10^8 m/s 300,000,000 m/s

What is the difference between sections on the electromagnetic spectrum?

Different wavelength and frequency

In which direction does frequency and wavelength change on the electromagnetic spectrum?

Wavelength decreases from radio to gamma Frequency increases from radio to gamma

What can be the region of wavelength for a radio wave?

From 1000m to 1m

What can be the region of wavelength for a gamma wave?

1000th of a nano meter

What can be used to see a wave and send it?

A transmitter and a oscilloscope and transmitter

What can be used to receive a radio wave?

A receiver and oscilloscope

What do mobile phones use and why?

Microwaves as they can penetrate through walls and only require a short aerial for transmission

What are the two types of satellites?

Low orbit satellites and geostationary satellites

What are the harmful effects of microwaves?

Internal heating of body cells

What are the harmful effects of infared?

Skin burn

What are the harmful effects of ultra violet?

Damage to skin and eyes leading to skin cancer and eye conditions

What are the harmful effects of X-rays or gamma rays?

Cell mutation or damage

What happens when waves travel through a gap?

It spreads out and diffracts

What is diffraction?

The spreading out of waves as they ‘bend around’ obstacles

What factors effect diffraction?

Wave length and gap size

What happens when gap size and wavelength change in diffraction?

Maximum amount of diffraction when they are equal Much wider gap is little diffraction Bit wider gap is diffraction only at edges

Explain how Bluetooth uses electromagnetic radiation.

Uses low energy radio waves to pass through walls

Explain how optical fibres use electromagnetic radiation.

Used for cable television and high speed broadband because visible light can carry high rates of data by interpreting the transmission at the other end. Uses total internal reflection

What is an analogue signal?

They show continuous variation and can take any value within a range

What is a digital signal?

A signal that can only take a certain value

What are the two ways a signal can be transmitted?

As a digital or analogue signal

What are the benefits of digital signalling?

Increased rate if transmission Increase range of transmission due to more accurate regeneration

What is signal regeneration?

The process of removing noise from a signal when it is received

What is the range of human hearing?

20Hz to 20000Hz

What is the nature of a sound waves?

Longitudinal waves that are caused by vibrating particles

Where does sound travel faster?

In solids, then liquids then gas

What is the speed of a speed of a sound wave in air?

350m/s

How can you determine speed of sound?

Place two microphones a couple metres a way and connect them to a dat logger Place a sound source on the same line Measure the distance between the microphones Find the differnece between time taken to hear sound and divide distance by time

How do changes in amplitude effect a sound wave?

Amplitude increases with loudness

How do changes in frequency effect a sound wave?

Higher the frequency the higher the pitch

What is an echo?

The reflection of a sound wave.

What is an ultrasound wave?

A sound wave with a frequency greater than 20000Hz

What are ultrasound waves used for?

Ultrasound scans on babies as can pass through soft tissue and the echo speed can be interpreted by a computer to make visual image Used to test materials for flaws Sonar by using echoes