Light and Sound Flashcards
Are sound waves transverse or longitudinal?
Longitudinal
Why are sound waves mechanical?
Need a substance to travel through
What do sound waves do to the ear drum and other solid parts of the human ear?
Make them vibrate
Why is there a limit to the range of human hearing?
Conversion of sound waves in air to vibrations in ear (solid) only works over a limited range of frequencies
What is the frequency range of normal human hearing?
20Hz to 20,000 Hz (20kHz)
What are ultrasound waves?
Sound waves with a frequency above 20,000 (Hz)
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 water
What are the properties of P-waves?
Longitudinal, travel through liquids and solids
What are the 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 convex lens?
Convex bulges out in the middle, concave is thinner in the middle than at the edges
What does a convex lens do to parallel rays of light?
Light converges (comes together) at the principal focus
What does a concave lens do to parallel rays of light?
Light diverges (spreads out) 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
