Electromagnetic waves

What type of spectrum do electromagnetic waves come from

What type of spectrum do electromagnetic waves come from

A continuous spectrum

Order the EM waves from lowest to highest frequency

radio waves

microwaves

infrared

Visible light

Ultraviolet light

X rays

Gamma rays

How do speed of em radiation differ from the vacuum and air

Em waves in the vacuum and air travel at the same speed

Health effects of x rays and gamma rays

Their Ionising radiation causes gene mutations

Lead to increased risk of various cancers

Uses of infrared radiation

Electrical heaters

Cooking food

Infrared cameras

how are radio waves produced

Oscillations in an electric circuit

Uses of microwaves

Satellites communicating

Cooking food

What are health effects of ultraviolet waves

Premature ageing of skin

Increase risk of skin cancer

Uses of radio waves

Television transmissions

Radio transmissions

What’s the wave phenomena where lenses form an image

Refraction

How do convex waves form an image

Parallel rays are refracted and brought together at a point called the principal focus

What is the focal length of a lens

Distance from the lens to the principal focus

Difference between the convex and concave Lens images

Convex lens produce real outs virtual images

Concave lenses can only produce virtual images

Why magnification doesn’t have an image

Ratio between the image height and object height

Ratios need no height

What determines the colour of visible light

The wavelength and frequency of light waves

Which colour has the highest frequency

Blue

What colour has the highest wavelength

Red

What’s specular reflection

Reflection from a smooth surface in a single direction

What’s diffuse reflection

Reflection from a rough surface which causes scattering

How do red filters work

A red filter absorbs all wavelength of light other than those in the red range spectrum

This means only red only passes through the filter

What determines the colour of an opaque object

Different objects reflect different wavelengths of light at different amounts

The most strongly reflected determines the colour

Where do you see white

If all wavelengths are reflected at equal amounts

Where do you see black

If all wavelengths are absorbed equally