P16 Light and Sound Flashcards
Are sound waves transverse or longitudinal?
Longitudinal
Why are sound waves mechanical?
Need a substance to travel through
What is the frequency range of human hearing?
20 Hz to 20,000 Hz
What are ultrasound waves?
Sound waves with a frequency above 20,000Hz
What happens to ultrasound waves when they meet a boundary between two substances?
They are partially reflected and some are transmitted
What is echo sounding used for?
Detecting objects in deep water
Measuring the depth of the water
Properties of P waves
Longitudinal
Travel through liquids and solid
Properties of S waves
Transverse
Cannot travel through liquids
Which observation suggests that the outer core of the Earth must be liquid?
S waves are not detected on the opposite side of the Earth
What is the difference between a concave and a convex lense?
Convex bulges out in the middle
Concave is thinner in the middle
What does a convex lens do to parallel rays of light?
Light converges at the principal focus
What does a concave lens do to parallel rays of loght?
Light diverges so they appear to have come from the principal focus
What is the focal length of a lens?
Distance from the centre of the lens to the principal focus
What kind of image do concave lenses produce?
Virtual
What kind of image do convex lenses produce?
Real or virtual
