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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
“ It does not do harm to the mystery to know a little about it.
Far more marvellous is the truth than any artists of the past imagined! ”
- Richard Feynman
It takes a little genius
Who was Richard Feynman?
“ Richard Feynman was to the second half of the 20 th century what Einstein was to the first: the perfect example of scientific genius”
Frank McLynn, Independent.
A new way of seeing
The truth about light
It comes in packets called photons.
They each have an energy E=hf
Dim blue light contains identical photons to bright blue light – just less of them.
We can never know the route a photo will take we can only calculate probabilities.
QUANTUM THEORY RECONCILES THESE FACTS WITH THE OBSERVED WAVE LIKE BEHAVIOUR OF LIGHT e.g. INTERFERENCE, DIFFRACTION ….
QUANTUM MODEL OF REFLECTION
Ask: In what ways can we…?
Assess the situation. Get the facts.
Generate possible solutions with green light, non-judgmental thinking.
Select the best solution.
Results table EXERCISE 1
Adding arrows. Finding probability.
TESTING THE THEORY
QUANTUM MODEL OF REFRACTION
EXERCISE 2 Homework ‘ try all paths refraction’