| Question | Answer |
|---|---|
| What happens if sound waves cross the boundary at an agle of 90 degrees? | They carry on straight |
| All angles are measured between light rays and the …… | Normal |
| How is infrared used in astronomy? | The universe contains vast amount of dust and infrared telescopes can peer into the hearts of dusty galaxies |
| What is refraction? | Refraction is the change in speed when light rays travel from one medium to another which can lead to a change in direction |
| What is the focal point? | The point in which the light rays meet |
| Describe how microwaves are used in radar systems | Radar works by transmitting a beam of microwaves, detecting the signals reflected back from objects in the path of the beam |
| What does a convex lens do to light rays? | Brings them together to a point |
| State a practical use of UV radiation | Steralizing work places |
| How do you calculate lambda? | v/f |
| Give 3 examples of communication systems that use microwaves | mobile phones, satellite tv and wifi and bluetooth |
| How do physiotherapists use infrared radiation? | They heat damaged tissues to help them heal quicker |
| How does sun tan lotion work? | It absorbs the shorter wavelength UV rays that cause sunburn and allow the longer waves to reach the skin creating a tan |
| How can you protect yourself from the harmful rays of the sun? | Sun-tan lotion |
| Why is too much exposure to UV rays bad for your health? | It can cause skin to burn and become painful |
| Why is UV radiation needed by the body? | To produce Vitamin D3, which allows calcium to be absorbed from our food |
| Name the EM spectrum | |
| Give an examople of the use of infrared images of earth from space | These images can provide an early warning for El Nino events and helo to prevent potential storms |
| What is a periscope used for? | Seeing around or over objects |
| What happens to parallel rays of light when they strike a concave mirror? | The rays will reflect inwards towards a focal point |
| What happens to parallel rays of light when they strike a convex mirror? | The rays will travel directly away from an imaginary focal point |
| How does the focal length of the lens affect the image that is formed by the lens? | The smaller the focal length the smaller the image |
| What is a lens? | A lens is an optical device which refracts light |
| Describe how radio waves can be produced | Naturally occuring radio waves can be produced by lightening. Unntatural radio waves are produced by radio transmitters |
| How are radio waves? | The size of buildings or people |
| How big are gamma rays? | The size of atomic nuclei |
| What does the whole EM spectrum have in common? | Travel at the speed of light |
| What is a medical use of radio waves | Radio waves can produced 3D images of the bodys organs and structures |
| Give two uses for Xrays | Can take images of bones and other body parts such as the brain or lungs |
| Describe how X-Rays work | X-rays are directed at the object to be imaged and some of the Xrays are absorbed as they pass through and then hit a photographic plate on the other side of the object to blacken it |
| Describe what happens when X-Rays strike a photographic film | They are absorbed through the body except where they are absorbed by dense structures like bone |
| What is a natural source of Gamma Rays | Gamma decay |
| What is irradiation? | The process in which an object is exposed to radiation |
| What type of waves are light waves? | Transverse |
| Give one example of how sound waves are different to light waves? | Light waves can travel through a vaccum |
| What does laterally inverted mean? | Letters and words look like they have been written backwards |
| How does light travel? | In straight lines |
| What is the law of reflection? | The angle of incidence is equal to the angle of reflection |
| What happens when light passes from a fast medium to a slow medium ? | It bends towards the normal |
| What happens when light passes from a slow medium to a fast medium? | It bends away from the normal |
| Give 3 examples where lenses are used | Microscopes, cameras, telescopes, projectors |
| How can the focal length of a concave lens be measured be measured? | Placing a lens in front of a screen and moving the lens until a sharp image of a distant object is obtained on the screen, then measuring the distance from the lens to the screen (this is the focal legnth) |
| How can you correct short sight? | A concave lens to spread the rays of light out before they enter the eye |
| How can you correct long sight? | A convex lens to bring the light rays together before entering the eye |
| What are prisms used for and how does this work? | To seperate white light into the spectrum of visible light – ROYGBIV. This works because different wavelegnths of light are refracted by slightly different amounts |
| What is the electromagnetic spectrum? | An oscillation of electrical and magnetic fields that travel through space as a wave and carries energy |
| How is the electromagnetic spectrum split up? | according to its wavelegnth ( or frequency) |
| How can you detect radio waves? | Aerial |
| How can you detect microwaves? | Aerial |
| How can you detect infrared? | thermochromic film |
| How can you detect visible light? | Photographic film |
| HOw can you detect ultraviolet? | Fluorescent chemicals |
| how can you detect x rays? | Photographic film |
| How can you detect gamma rays? | Photographic film |
| How is ultraviolet radiation used in forensics? | For looking at fingerprints |
| What happens to the focal legnth when you increase the thickness of the lens ? | The focal length decreases |
| What is the scientific word for short and long sighted? | Short – myopia . Long – hypermetropia |
| If you were to put a convex lens in front of a window and a screen behind the lens to produce an image of the window, what 3 things would you notice about this window? | Upside down, smaller, back to front |
| When is the angle of refraction greater than the angle of incidence ? | When light leaves a medium as it is bent away from the normal |
| What is the angle of incidence? | The angle between the incident ray and the normal |
| Which colour is refracted the least and why? | Red because the short the wavelegnth of the light, the more it is refracted |
| What does medium mean? | Another word fo material |
| What is light ? | An electromagnetic wave that is visible to the human eye |
| What is a converging and diversion lens | Convex and concave (in order ) |
| What can a short sighted person see | Short sighted people can see objects clearly in front of them but struggle to see objects from far awag |
| What two surfaces are great at absorbing and reflecting infrared radiation? | Black and shiny surfaces |
| What materials can microwaves pass through? | Plastic and glass |
| Why can microwaves not travel through metals? | Because metals reflect microwaves |
| Out of UV A, B and C, which has the higher frequency? | UV C |
| What is the most dangerous type of UV radiation? | UV C |
| What two types of waves make an Amplitude Modulation Wave | Audio Signal and Carrier Wave |
| What are transverse waves? | Transverse waves are where the vibrations are at right angles to the direction of travel |
| What are longitudinal waves? | Where the vibrations are in the same direction to the direction of travel |
| What is amplitude modulation? | A technique used to transmit sound information via radio waves |
| Why are CAT scanners now used instead of X-Rays more? | Because they produce much more data and detail |
| What safety precausions are made when using X rays? | Not only are patients limited to the amount of X rays they are allowed to have but hospital staff must wait outside a room with a shielded lead infused wall for max protection |
| What is diffraction? | The bending of waves around obsticles and openings |
| What is the focal legnth? | The distance between the lens and the image sensor when the subject is in focus |
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