physics test - y9

Lenses

Optical devices that work by refracting light to form images.

Refraction

The bending of light as it moves through different surfaces.

Focal Point

The point where parallel rays of light converge after passing through a lens.

Focal Length

The distance between the center of the lens and the focal point.

Myopia

A condition of short-sightedness treated with diverging lenses.

Hyperopia

A condition of long-sightedness treated with converging lenses.

Sound

A longitudinal mechanical wave produced by vibrating objects.

Vacuum

A space where sound cannot travel.

Speed

Calculated using the formula distance/time.

Volume of Sound

Determined by amplitude; higher amplitude means higher volume.

Frequency

Determines pitch; higher frequency results in higher pitch.

White Light

A spectrum of colors including red, orange, yellow, green, blue, indigo, and violet.

Transverse Waves

Waves that oscillate perpendicular to the direction of energy transfer.

Radio Waves

Waves with the lowest frequency and shortest wavelength, used in remote controls.

Microwaves

Waves that cause water molecules to vibrate and can heat human tissue at high intensity.

Infrared (IR) Waves

Used in thermal imaging and can cause skin burns; contribute to global warming.

Ultraviolet (UV) Waves

Cause suntans and sunburns; used for sterilization; can cause skin cancer.

UVA

Low-energy UV radiation, less dangerous.

UVB

High-energy UV radiation, causes sunburns and skin cancer.

UVC

Very dangerous UV radiation, blocked by the ozone layer.

X-rays

Can penetrate soft tissue but are absorbed by bone, used for detecting injuries.

Gamma rays

Highest energy and frequency waves, emitted by radioactive materials, used in radiotherapy.

Water Waves

Transverse waves where oscillation is perpendicular to wave direction.

Reflection

The bouncing back of light from surfaces, following the law of reflection.

Law of Reflection

States that the angle of incidence equals the angle of reflection.

Refraction

The bending of light as it passes through transparent materials.