High School Grade 12 Physics Question

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Physics 30 Unit 5 Atomic Structure Exam Part B

Name: __________________ Date: ________________ Written Response #1 Use the following information to answer the next question.

• Draw the electric field lines showing the electric field direction and shape

between the parallel plates above. (1 mark)

• Determine the magnitude and direction of the acceleration on the charged particle. (4 marks)

An oil-drop, that has a mass of 3.5 × 10-15 kg and an excess of 7 electrons, is located between horizontal parallel plates. The plates are separated by a distance of 2.5 cm and have and potential difference of 4.8 × 102 V between them. Positively charged plate Charged Particle Plate separation = 2.5 cm Negatively charged plate

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Name: ______________

• Describe one change that could be made to the above experiment so that the charged particle will be now be suspended. Explain how the change will allow the particle to be suspended and justify your answer with appropriate formulas (3 marks)

• Determine the time required for the particle to move from the upper plate to the lower plate when the particle begins at rest. (2 marks)

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Written Response #2 Name: ____________ Use the following information to answer the next question.

The northern lights that are visible in Alberta skies on many winter nights are produced when free electrons in the solar wind are trapped within Earth’s magnetic field.

Diagram I: Solar Wind and Earth

These free electrons can collide with atomic oxygen in the upper atmosphere. As a result of these collisions, atoms of oxygen become excited and electrons in lower levels move to higher energy levels. Electron transitions toward the ground state result in the emission of photons, two of which correspond to red and green light. The following diagram shows the three energy levels of atomic oxygen involved in the production of green- and red-colored northern lights.

Diagram II: Selected Electron Energy Levels

In addition to the two photons identified above, a third unique photon can be emitted by atomic oxygen after it has been excited to energy level C.

Geographic North Pole

Equator

Geographic South Pole

Solar Wind

Energy Level C

Energy Level B

Energy Level A

Electron Transition

Electron Transition

Photon emission

Photon emission

_____ eV _____ eV

-15.82 eV Ground State

fgreen = 5.379 × 1014 Hz

fred = 4.762 × 1014 Hz

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Name: ______________

• Draw several magnetic field lines on diagram I to show the shape, strength and direction of the Earth’s magnetic field. (1 mark)

• Determine the energy of the photon of red light and the energy of the photon of green light. (2 marks)

• Determine the energy values in units of electron volts for the energy level B and energy level C of atomic oxygen. (2 marks).

If you are unable to determine the energy values for levels B and C, use the hypothetical values of energy level B = -13.10 eV and energy level C = -11.20 eV for the rest of the question. • Determine the minimum speed of a free electron that would excite atomic

oxygen from energy level A to energy level B. (2 marks)

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Name: __________

• Draw an arrow on diagram II to show the electron transition that corresponds to the emission of the third, unique photon. (1 mark)

• Determine the wavelength of the third, unique photon, and identify the region of the electromagnetic spectrum to which this photon belongs. (3 marks)