3. Wave nature of light This image is of a bright light photographed through 'crossed gratings' – two diffraction gratings set perpendicular to one another.
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5. Taylors experiment A 0.3 W bulb emits about 0.001 W of visible light at say 6 X 10 14 Hz. Calculate the number of photos emitted each second. E=hf = 4 X 10 -19 J so 2.5 X 10 16 emitted per second At 30cm away, about 1 photon in 5000 enters the eye. Calculate how many photos enter per second and then their average spacing. 2.5 X 10 -19 / 50 000 = 5 X 10 11 this is one every 2 X 10 -12 s. Separation = 2 X 10 -12 X 3 X 10 8 = 6 X 10 -4 m A filter is used to reduce the intensity to 10 -4 of original value, what is the new spacing? Separation increases by 10 4 so now 6 m