Date | May 2018 | Marks available | 3 | Reference code | 18M.2.HL.TZ2.5 |
Level | Higher level | Paper | Paper 2 | Time zone | Time zone 2 |
Command term | Sketch | Question number | 5 | Adapted from | N/A |
Question
Monochromatic light from two identical lamps arrives on a screen.
The intensity of light on the screen from each lamp separately is I0.
On the axes, sketch a graph to show the variation with distance x on the screen of the intensity I of light on the screen.
Monochromatic light from a single source is incident on two thin, parallel slits.
The following data are available.
\[\begin{array}{*{20}{l}} {{\text{Slit separation}}}&{ = 0.12{\text{ mm}}} \\ {{\text{Wavelength}}}&{ = 680{\text{ nm}}} \\ {{\text{Distance to screen}}}&{ = 3.5{\text{ m}}} \end{array}\]
The intensity I of light at the screen from each slit separately is I0. Sketch, on the axes, a graph to show the variation with distance x on the screen of the intensity of light on the screen for this arrangement.
The slit separation is increased. Outline one change observed on the screen.
Markscheme
horizontal straight line through I = 2
Accept a curve that falls from I = 2 as distance increases from centre but not if it falls to zero.
[1 mark]
«standard two slit pattern»
general shape with a maximum at x = 0
maxima at 4I0
maxima separated by «\(\frac{{D\lambda }}{s}\) =» 2.0 cm
Accept single slit modulated pattern provided central maximum is at 4. ie height of peaks decrease as they go away from central maximum. Peaks must be of the same width
[3 marks]
fringe width/separation decreases
OR
more maxima seen
[1 mark]