Paper 1 - Weak Points Flashcards
What interaction produces strange particles?
The strong interaction
What interaction do strange particles decay through?
The weak interaction
T/F: EM waves travel at different speeds in a vacuum dependent on their wavelength
False: all EM waves travel at the same speed in a vacuum
Define polarisation
The process of restricting the oscillations of particles in a transverse wave to one plane that is still perpendicular to the direction of wave propagation or energy transfer
Why can polarisation only take place in traverse waves?
Particles cannot oscillate in more than one plane in longitudinal waves because they have to oscillate parallel to the direction of wave propagation or energy transfer
What are the two directions of polarising a transverse wave?
Vertically or horizontally
Why might you see no wave transmitted after polarising it?
Because it only had components in one plane originally and they were both polarised
What is plane polarisation?
Another name for polarisation in which the oscillations of particles in a transverse wave are restricted to one plane perpendicular to the direction of wave propagation or energy transfer
What do you see if you rotate a polariser through 360 degrees?
Peaks and troughs in the intensity of the wave that looks like a sin curve
What happens to the intensity of a polarised wave?
It decreases
Which property of a wave changes when it diffracts?
The amplitude
How does the amplitude of a diffracted wave change?
The amplitude of the diffracted wave is less than that of the incident wave because the energy is distributed over a wider area
Why does diffraction occur?
When a wave passes through an aperture it is forced to curve and this causes it to interfere
What does the interference pattern formed by diffraction look like?
The interference pattern has one large and bright central maxima and then several dark fringes that have decreasing intensity on either side of it
What does the interference pattern look like if you diffract white light?
There is a central white maxima with a spectrum on either side of it
What happens to the interference pattern if you increase the wavelength of light?
You increase the angle of diffraction meaning the interference pattern gets more spread out, the fringes get wider and dimmer so fewer maxima can be seen
T/F: Increasing the wavelength has the same effect on the interference pattern as decreasing the slit width in diffraction
True
What is material dispersion?
When different wavelengths of light take different amounts of time to travel through the optical fibre because they travel at different speeds in the core