Waves on a Electromagnetic Spectrum

Flashcards about Waves on a Electromagnetic Spectrum.

Electromagnetic Waves

Transverse waves that transfer energy from the source to an absorber.

Properties of EM Waves

Transverse, travel through a vacuum, same speed in a vacuum.

Electromagnetic Spectrum

Arranged by wavelengths or frequencies, from longest wavelength (lowest frequency) to shortest wavelength (highest frequency).

Visible Light

Range of wavelengths visible to humans, only 0.0035% of the EM spectrum.

Wavelength and Color

Red has the longest wavelength, violet has the shortest.

Energy Transfer by EM Waves

Shorter wavelength carries a higher energy (UV, X-rays, gamma rays).

Energy Transfer by Microwaves

Water molecules absorb microwave radiation.

Energy Transfer by Infrared

Hot objects emit infrared radiation.

Refraction

Change in direction when light passes between two transparent media.

Normal Line

Hypothetical line perpendicular to the surface of boundaries.

Refraction Direction

From less dense to more dense, light bends towards the normal; from more dense to less dense, light bends away.

Infrared Radiation Experiment Variables

Independent: Colour; Dependent: Temperature; Controls: Identical flasks, same amount/temperature of water, same time interval.

Factors Affecting Thermal Radiation

Temperature, surface area, and colour of the body.

Systematic Errors in Radiation Experiment

Starting temperatures not the same, errors in timing.

EM Waves & Atoms

Atoms can absorb or emit EM waves.

Hazardous Effects of High-Energy EM Waves

Can ionise atoms, causing damage to human tissue (UV, X-rays, gamma rays).

Radiation Dose

Measure of risk of harm from exposure to ionising radiation, measured in sieverts (Sv).

Microwave Dangers

Risk of internal heating due to water absorption.

UV dangers

Severe eye damage, premature ageing, skin cancer.

X-rays & Gamma Rays Dangers

Cause mutation of genes and cancer.

Lenses

Piece of equipment that forms an image by refracting light.

Convex Lens

Converging lens, brings parallel rays to a focus (principal focus).

Concave Lens

Diverging lens, makes parallel rays diverge from a point.

Real Image

Formed when light rays converge and meet, can be projected, always inverted.

Virtual Image

Formed when light rays appear to meet, cannot be projected, always upright.

Colour Filters

Absorb certain wavelengths and transmit others.

Opaque Object Colour

Determined by which wavelengths are more strongly reflected.

Black Body Radiation

Thermal radiation emitted by all objects.

Perfect Black Body

Object that absorbs all radiation, does not reflect or transmit any.

Greenhouse Effect

Natural process that warms the Earth's surface from the Sun through absorption and re-radiation by greenhouse gases.