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ASPhysicsOCRExam Questions4. Electrons, Waves & Photons4.11 Photons & Wave-Particle Duality

Photons & Wave-Particle Duality (OCR AS Physics)

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4.11 Photons & Wave-Particle Duality

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4.11 Photons & Wave-Particle Duality

1a2 marks
a)
The Planck constant h is an important fundamental constant in quantum physics.

Determine the S.I. base units for h.




base units = ....................................... [2]

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1b9 marks
b)
A researcher is investigating the de Broglie wavelength of charged particles.

The charged particles are accelerated through a potential difference V. The de Broglie wavelength λ of these particles is then determined by the researcher.

Each particle has mass m and charge q.

i)
Show that the de Broglie wavelength λ is given by the expression lambda to the power of 2 space end exponent equals fraction numerator h squared over denominator 2 m q end fraction cross times 1 over V

[2]

ii)
The researcher plots data points on a λ2 against 1 over V grid, as shown below.

q19b-ii-paper-2-nov-2020-ocr-a-level-physics

1
Calculate the percentage uncertainty in λ for the data point circled on the grid.




percentage uncertainty = .................................... % [2]

2
Draw a straight line of best fit through the data points.

[1]

3
The charge q on the particle is 2e, where e is the elementary charge.
Use your best fit straight line to show that the mass m of the particle is about 10−26 kg.

[4]

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