IB PhysicsTheme C--Qc#10-11-Paper 2-Diffraction-Resolution and standing waves

This question is about diffraction and resolution.
Monochromatic light is incident normally on a single narrow slit and gives rise to a diffraction pattern on a screen.
Sketch, for the diffraction pattern produced, a graph showing the variation of the relative
intensity of the light with the angle measured from the centre of the slit.
- The single narrow slit is replaced by a double narrow slit. Explain, with reference to your answer to (a), how the Rayleigh criterion applies to the diffraction patterns produced by the light emerging from the two slits.
c. Two lamps emit light of wavelength 620 nm. The lights are observed through a circular aperture of diameter 1.5 mm from a distance of 850 m. Calculate the minimum distance between the lamps so that they are resolved.
2. This question is about standing (stationary) waves.
The diagram shows an arrangement used to produce a standing (stationary) wave on a stretched string of length 2.4 m. A standing wave with five loops appears when the frequency of the oscillator is set to 150 Hz, as shown below.
a. State the name given to point X on the string.
(i) Calculate the speed of the wave along the string.
(ii) Calculate the frequency of the oscillator that would produce a standing wave with two loops on this string.
Topic 4 and topic 9 Oscillations and waves playlist: