Nature of waves Flashcards
1
Q
Loudspeaker interference.
A
- If two loudspeakers are connected to the same output of an oscillator and placed about 1 m apart, you will hear alternate loud and quiet areas if you move along a line in front of them.
- When two crests or two trophs overlap, the waves are in step and the sound will be loud.
- When a troph and a crest overlap, the waves are out of step and the sound will be quiet.
2
Q
Constructive interference.
A
- Constructive interference means that the waves meet in phase.
- Constructive interference occurs when the path difference between the two sources is a whole number of wavelengths.
3
Q
Destructive interference.
A
- Destructive interference means that the waves are out of phase.
- Destructive interference occurs when the path difference between the two sources is an odd number of wavelengths.
4
Q
Narrow slit experiment.
A
- Interference between light waves is produced when light diffract as it passes through narrow slits.
- Bright bands are constructive interference.
- Dark bands are destructive interference.
- The wavelength of light is between 0.0004 mm and 0.000 6 mm so the slits have to be very narrow.
5
Q
Explaining interfence of light.
A
Interference of light can only be explained if light is a wave.
6
Q
Polarisation.
A
- Electromagnetic waves, such as light, are transverse waves. Oscillations occur in all directions at right angles to the wave direction.
- Light is polarised if the oscillations are only in one direction at right angles to the wave direction.
- Polaroid sunglasses stop oscillations in all but one direction at right angles to the wave. This reduces the amount of light passing through.
7
Q
Newton and Huygens Ideas on light.
A
- Newton thought of light as a particle. If he was correct, then light should travel faster in a denser medium.
- Huygen thought of light as a wave. If he was correct, then light should travel slower in a denser medium.
- When the speed of light was finally measured, Newton was proved wrong.
