Waves Flashcards
(12 cards)
Explain why a signal strength may fall to a minimum
A path difference of (n+0.5) wavelengths creates a phase difference and destructive interference
what happens to intensity maxima if you increase wavelength
they become more widely spaced
Effect on intensity maxima if you increase distance from screen to grating
more widely spaced
How do you reduce uncertainty when using a diffraction grating ?
Use a higher order spot, increase value therefore smaller percentage uncertainty
How are stationary waves formed in a microwave oven
Waves are reflected off oven wall
they superpose/ interfere with waves travelling in the opposite direction
Why does chocolate only melt in select places when not spinning in microwave?
Melts as the points of highest energy: anti nodes
Why does microwave spin?
To move antinodes/ maximum energy around to heat throughout
Why does minimum intensity not actually reach zero?
Energy is lost / intensity drops as it propagates
One wave travels further than the other,
amplitudes don’t cancel fully
When wind blows, stationary waves are formed on a wire. Why can only specific frequencies form?
Wind produces a wave on the wire
Wave is reflected at each end so waves travelling in opp directions
waves interfere / superpose
only certain freq because ends must be nodes
Why might a wire under tension sag when the high wind stops
copper may be stretched beyond its elastic limit
permanent length change
How to reduce percentage error with the diffraction grating?
increase grating distance to screen to increase y measurement with some effect
Polarised sunglasses are reliant on?
Reflected light is plane polarised
