Topic 6 - Waves Flashcards
What is amplitude?
The maximum displacement of a wave from its undisturbed (equilibrium) position.
What is Angle of Incidence?
The angle between the incident ray and normal.
What is Angle of Reflection?
The angle between the reflected ray and normal.
What does black mean?
An object will appear black if it absorbs all wavelengths of radiation incident on it.
What are colour filters?
Filters that absorb certain wavelengths (colours) and transmit others. A blue filter for example will absorb all wavelengths other than those in the blue region of the colour spectrum.
What is colour?
Colour is determined by frequency and wavelength.
What is Constant Temperature?
A body remains at a constant temperature if it is
absorbing radiation at the same rate that it is emitting it.
What is a Convex lens?
A lens that brings parallel rays to focus at the principal focus. The image formed can be either real or virtual.
What is a diffuse reflection?
Reflection from a rough surface that results in scattering.
What is echo sounding?
A technique that uses high frequency sound waves to
detect objects in deep water and to measure the depth of water.
What are electromagnetic wave?
Transverse waves that transfer energy from the source of the waves, to an absorber. They form a continuous spectrum of different frequencies and all travel at the same speed in a vacuum.
What is a focal length?
The distance between the centre of a lens and its principal focus.
What is a frequency?
The number of waves passing a given point in a second. It is the inverse of the wave’s period.
What is Hertz?
The unit of frequency?
What is Human Hearing?
Humans can hear sounds in the frequency range of 20Hz
to 20kHz.
What is infrared radiation?
A type of radiation that all objects emit and absorb. The hotter an object is, the greater the infrared radiation it emits in a given time.
What is infrared?
Used for cooking food, electrical heaters and infrared imaging.
What is ionising radiation?
Radiation that can cause the mutation of genes and cause
cancer. X-rays and gamma rays are both forms of ionising radiation.
What is a lens?
An object that forms an image through the refraction of light.
What are longitudinal waves?
Waves with oscillations that are parallel to the direction of travel/ energy transfer.
What is magnification?
The ratio of the image height over the object height for a lens. Since it is a ratio, it has no units.
What are microwaves?
Used for satellite communications and for cooking food.
What is a normal?
The normal is an imaginary reference line that is constructed perpendicular to a boundary at the point that the wave intercepts it.
What are P- Waves?
Longitudinal, seismic waves that travel at different speeds through solids and liquids.
What is a perfect black body?
An object that absorbs all radiation incident on it and does not reflect or transmit any type of radiation.
What is a period?
The time it takes for one complete wave to pass a given point. It is the
inverse of frequency.
What is radiation dose?
A measure of the risk of harm to the body as a result of radiation exposure.
What are radio waves?
Used for television and radio signals. They can be produced by oscillations in electrical circuits.
What is a reflection?
Reflection is when a wave bounces off a boundary. The angle of incidence always equals the angle of reflection.
What is a S- Wave?
Transverse, seismic waves that cannot travel through liquids.
What are seismic waves?
Waves that are produced by earthquakes.
What are sound waves?
The longitudinal waves responsible for sound. In solids, sound waves are transmitted by the vibrations of the solid’s particles.
What is specular reflection?
Reflection from a smooth surface, in a single direction.
What is a transverse wave?
Waves with oscillations that are perpendicular to the direction of travel/ energy transfer.
What is a ultrasound scan?
A technique that involves ultrasound waves being
transmitted and then partially reflected at a boundary before being detected by a detector. The time between transmission and detection can be used to
calculate distances, and build up an image.
What are ultrasound waves?
Waves that have a frequency higher than the upper limit
of human hearing (20kHz).
What is ultraviolet?
Used in energy efficient lamps and for sun tanning.
What is visible light?
The only type of electromagnetic radiation that our eyes can detect.
It is used for fibre optic communications.
What is wave speed?
The speed at which energy is transferred through the medium. It is equal to the product of the wave’s wavelength and frequency.
What is a wavelength?
The distance from a point on one wave to the same point on the adjacent wave (i.e. peak to peak or trough to trough).
What is white?
An object will appear white if it emits all wavelengths equally.
What are the two parts of a longitudinal wave called?
Compression and rarefactions.
How do sound waves travel through a solid?
The particle sin the solid vibrate and transfer kinetic energy through the material.
What technique is used to detect objects in deep water and measure water depth?
- Echo Sounding
- High frequency sound waves are emitted, reflected and detected
- Time differences between emission and detection, alongside wave speed, are used to calculate distances
Order the type of electromagnetic radiation rom lowest to highest frequency.
- Radio waves
- Microwaves
-Infrared - Visible Light
- Ultraviolet
- X- rays
- Gamma Rays
how can radio waves create an alternating current in a circuit?
When radio waves absorbed, they can induce oscillations in a circuit with the same frequency as the wave themselves.
What health effects can X- rays and Gamma Rays cause?
- They are ionising radiation so can cause mutations in genes
- They can lead to increased risk of developing various cancers
What is the difference between the image produced by a convex and a concave lens?
- Convex lenses can produce real or virtual images
- Concave lenses can only produce virtual images
What determines the colour of an opaque object?
- Different objects reflect different wavelengths of light by different amounts
- The wavelength that are most strongly reflected determine the colour
Why is a perfect black body the best possible emitter of radiation?
- It is a perfect absorber since it absorbs all radiation incident on it
- A perfect absorber is also a perfect emitter
Give two factor that affect the temperature of the earth?
- The earth’s rate of absorption and emission of radiation
- The amount of reflection of radiation into space
