# GCSE - PHYSICS - WAVES

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• Created by: dp1828
• Created on: 28-06-15 17:49
What are the similarities between the waves in the EM spectrum?
They all travel at the same speed through a vacuum (space). They all move energy from one place to another. They all travel in a straight line.
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What are the differences between the waves in the EM spectrum?
They are absorbed, reflected and transmitted differently. They have different effects on living cells. The different waves have different wavelengths and frequencies.
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What is the EM spectrum?
The Electromagnetic Spectrum is a continuous group of waves that have some similar properties, like they all travel at the same speed of light and they can be reflected. Depending on their frequency though they have different uses.
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How do microwaves cook food?
Microwaves can be used in cooking because many foods contain water molecules. Microwaves of the right wavelength are able to make the water molecules resonate. This causes the food to get hot.
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What do sound and EM waves do when they reach a gap or corner?
Sound and EM waves can diffract or spread out when they reach a gap or corner. This effect is largest when the gap is similar in size to the wavelength of the wave.
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It travels as waves and moves energy from one place to another.
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Design an experiment to investigate the hazards of using a mobile phone. Remember humans are not normally involved in early health and safety tests.
You can design a mould of a human head and fill it with tissue. Then place the mobile phone on it and then look at the damage it has done to the tissue in the head.
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What advice would you give to phone users while you complete your safety tests?
I would tell them not to use their phones that much for calls.
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How could you reassure the public that mobile phones are safe?
The waves are split in groups depending on their frequency. The frequency is usually a long wave length.
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What is the link between the energy carried by electromagnetic waves and their position in the spectrum?
The high energy waves are at the short wave length end of the spectrum.
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How can protection from radiation be achieved?
You can: reduce exposure time, increase distance from the source, shielding from the source and containing the source to prevent contact.
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What advice would you give to a regular mobile phone user who was concerned about mobile phones and health?
I would say try not to use your mobile phone to talk on a lot, if you do don't hold your phone close to your ear put it on speaker.
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Would the advice to someone living close to a mobile phone transmitter be different?
Yes because those signals used to make a call are going around the environment.
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Are mobile phones safe?
(Reasons may vary) I think it depends on how you use them, if you only use them to text people then I think they are fine to use.
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How can waves be grouped?
Waves can be grouped by how the particles move to transfer this energy.
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In a transverse wave, how do the particles vibrate?
Up and down.
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In a longitudinal wave, how do the particles vibrate?
Back and forth.
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What is the wavelength (λ) of a wave?
It is the distance between two consecutive points on a wave. Unit = metres.
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What is the frequency (f) of a wave?
It is the number of waves generated or passing a point each second. Unit = Hertz
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What is a plane mirror?
Flat mirror
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What is the angle of incidence?
Angle it goes in at
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What is the angle of reflection?
Angle it goes out at
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What is a virtual image?
An image that is not really there. When the light rays appear to come but don't actually come from that image like a mirror.
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What is a real image?
An image that can be projected. An image that is formed when the light rays are focused.
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What is the normal?
It is the line at 90 degrees to the surface (perpendicular). When a ray of light is at the normal line, it means it is travelling in a straight line.
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What is refraction?
When light and other waves change speed when they travel from one transparent to another. Refraction of light is the change of direction of a light ray when it crosses a boundary between two transparent substances.
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How far are the most distant galaxies?
13,000 million light years away.
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A big bang, a massive explosion from a very small point.
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What is CMBR?
Cosmic microwave background radiation. It was created just after the big bang.
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What type of wave can be produced on a stretched string?
A standing wave.
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Where are angles always measured between?
The ray and the normal to the surface.
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What does the law of reflection state?
When a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
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Why does light split up into different colours when it passes through a triangular prism?
They change speed when they pass across substances with different densities.
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What is the frequency range for the normal human ear?
20Hz
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Sound waves are what type of wave?
Longitudinal wave.
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What is white light?
Colourless light. Ordinary daylight.
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What are the colours of white light?
Red, yellow, orange, green, blue, indigo and violet.
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What waves are all used for communication?
Radio waves, microwaves, visible light and infrared.
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They are made by lightning or astronomical objects.
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What is optical fibre?
A thin glass fibre through which light can be transmitted.
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What can V = f x λ be used to calculate?
It can be used to calculate the frequency or wavelength of electromagnetic waves.
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What is red - shift?
Light observed from distant galaxies has been 'shifted' towards the red end of the spectrum.
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## Other cards in this set

### Card 2

#### Front

What are the differences between the waves in the EM spectrum?

#### Back

They are absorbed, reflected and transmitted differently. They have different effects on living cells. The different waves have different wavelengths and frequencies.

### Card 3

#### Front

What is the EM spectrum?

### Card 4

#### Front

How do microwaves cook food?

### Card 5

#### Front

What do sound and EM waves do when they reach a gap or corner?