GCSE Waves

what is a transverse wave

when the displacement is at a right angle to the direction of the wave

what is a longitudinal wave?

when the displacement is parallel to the direction of the wave

define wavelength

the distance between two peaks/points on a wave

define amplitude

the height of a wave. the greater the amplitude, the greater the energy

define frequency

the number of waves that pass a given point in one second (Hz)

define time period

the time taken for a wave to pass a specific point. time period = 1/frequency

give the formula for wave speed

wave speed = frequency x wavelength

define ultrasound

a high frequency sound wave (higher than 20,000Hz)

what is the hearing range for a younger person?

20-20,000Hz

What is an echo?

a reflected sound wave that returns to the origin

give the formula for echo

speed = 2 ÷ distance/time

What is a P-wave?

the first wave on a seismograph. it is longitudinal.

What is a S-wave?

The second wave on a seismograph. it is transverse and travels slower than the P wave

why do p-waves bend and refract?

P-wave's speed changes as they get deeper. they refract because the outer core is liquid and the mantle is solid

Why do S-waves stop at the outer core?

S-waves are transverse waves and can't travel through liquid

what is a shadow zone?

an area where neither P or S waves can be detected using a seisometer

Concave lenses are...

diverging lenses.

convex lenses are...

converging lenses.

what is a focal length?

The distance from the centre of the lens to the principal focus

what type of image can a convex lens produce?

real and virtual

what type of image can a concave lense produce?

virtual image

how do you identify a real image

image appears on the other side of the object, can be projected onto a screen

how do you identify a virtual image?

image appears on the same side as the other side of the object, cannot be projected onto a screen

how do you identify an inverted image

the triangle will be on the other side of the principal axis

how do you define a diminished/magnified image

the image/object arrow will be smaller/bigger than the other

order of electromagnetic spectrum

radio-->microwave-->infared-->visible-->UV-->xray-->gamma ray

way to remember order of electromagnetic spectrum

red martians invade venus using xray guns

what is black body radiation?

the radiation emitted by a perfect black body

what is a perfect black body?

an object that emits all the radiation it absorbs. the closest thing to a perfect black body is a black hole