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## wave optics

### (8 points)6. Series 27. Year - E. gelatinous speed of light

Determine the speed of light in a translucent gelatinous cake that you will make yourself. Don't forget to describe what its composed of.

Hint: Get yourself a microwave or a laser

Karel was going through different physical websites on the internet and found http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p009.shtml

### (5 points)6. Series 27. Year - P. light according to the norms

Design a placement of lights over a table so that you will fulfill the norms for lighting. You have enough compact fluorescent lamps with a luminous flux of $P=1400lm$. Norms say that for usual work the lighting of the workplace should be $E=300lx$. The lamps can be placed into any position on the ceilling at a height of $H=2\;\mathrm{m}$ over the work desk. For simplicity's sake one can consider a square work area that has a side of $a=1\;\mathrm{m}$ a consider the lamp to be an isotropic source of light. Neglect reflection and dispersion of light.

Karel was thinking about the norms of the EU.

### (8 points)1. Series 27. Year - E. bend it but don't bend it!

Your task is to measure the spacing of a diffraction grating using the light from three different LED-diodes. In case your interested, send us an email at experiment@fykos.cz and we will send you the LED diodes, resistor, wires, and, of course, the diffraction grating. The only thing you will need to buy is a 9 V battery.

Karel spent all of our budget.

### (5 points)1. Series 26. Year - 5. Young cylinder

Consider the classical Double-slit experiment but assume that the screen behind the two slits is cylindrical. The axis of this cylinder is parallel with the the two slits and the whole apparatus is symmetrical. This axis is at a distance $L$ from the slits, radius of the cylindrical screen is $R=L⁄2$ and the separation of the two slits is $a$. Describe the diffraction pattern on the screen after it has been unrolled from the cylinder and give the locations of diffraction maxima using a coordinate corresponding to the distance on the cylinder's surface.

Terka enjoys optics.

### 6. Series 24. Year - 2. evil triangle

Let's have a long slit with a little hole next to it. Describe the interference pattern that you observe on a screen behind this aperture if you illuminate it with coherent light. You can neglect diffraction of light both due to the hole and due to the slit.

### 5. Series 24. Year - 1. warm up

• blood sedimentation