PHYS 234 Fall 2021 Final Exam

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Purdue University *

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Course

234

Subject

Chemistry

Date

Dec 6, 2023

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pdf

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Uploaded by DeanOxidePolarBear24

Final Exam Page 1 NAME: Signature: PURDUE ID Number: PHYS 234 Fall 2021 Final Exam Friday 17 th December 2021 1. There are a total of 9 pages on this exam. Please write your name on each one. a. Page 2 contains potentially useful equations and constant. b. Pages 3-8 contain 32 multiple choice and true/false questions, each worth one point. Please mark your answers for these questions clearly on the bubble sheet provided. c. Page 9 contains an estimation problem worth 8 points. Please write your entire answer on the page provided. You may use the back of the page if you need more room. 2. When you are asked to write an explanation, you will be graded on depth, coherence, and clarity. Correct answers with incomplete explanations will not get full credit. 3. Raise your hand if you have a question. 4. This is a closed book test. You may not use any notes or equation sheets. You may use a calculator provided it is not capable of accessing the internet.

NAME:______________________________________________________________________ Final Exam Page 2 Equations and constants: Metric system: 1 cm = 10 -2 m, 1 mm = 10 -3 m, 1 μm = 10 -6 m, 1 nm = 10 -9 m, 1 pm = 10 -12 m. Power: ࠵? = ! ∆# = $ # : (units: 1 Watt = 1Joule/second = 1 Ampere ° Volt) Gravity: F = mg , U = mgh , g = 10 m/s 2 Universal gravitation: ࠵? = %&’ ( ! , ࠵? = 6.67 × 10 )** +’ ! ,- ! First law of thermodynamics: Δ E = Q + W Heat engine efficiency: (actual) ࠵? = ࠵?/࠵? . // (theoretical) ࠵? ’/0 = 1 − 1 " 1 # Second law of thermodynamics: Δ S ≥ 0 spontaneously. The number of ways of obtaining n heads out of N fair coin flips is N !/[ n !( N - n )!]. Ideal gas: pV = Nk B T , Δ E = 3 Nk B T /2. Snell’s law: n 1 sin θ 1 = n 2 sin θ 2 . Lens equation: * 2 = * 3 $ + * 3 % Magnification: |࠵?| = 3 3 % 3 $ 3 , exact expression is ࠵? = − 3 % 3 $ = 4 % 4 $ Real image: ࠵? 5 > 0; Virtual image: ࠵? 5 < 0 Double-slit experiment: Δ y = λL / d . Photons: E = hf , fλ = c , c = 3 × 10 8 m/s, h = 6.6 × 10 -34 J ° s, ( hc = 2 × 10 -25 J ° m) de Broglie wavelength: ࠵? = 4 6 = 4 ’7 Electrostatic constant: ࠵? 8 = 9 × 10 9 ࠵? ∙ ࠵? : ࠵? : = Point charges: F = k C qQ / r 2 , E = k C q / r 2 , U = k C qQ / r , V = k C q / r Electric field and potential: E = – d V /d x . Parallel plate capacitor: C = A /(4π k C d ). Ohm’s law: V = IR . Electrical power: P = I 2 R = IV = V 2 / R RC circuit time constant: ࠵? = ࠵?࠵? (units: 1࠵? ∙ 1࠵?࠵?࠵?࠵?࠵? = 1 second)

NAME:______________________________________________________________________ Final Exam Page 3 Multiple Choice: Select the best answer and mark it on the bubble sheet – one point each 1. The circuit to the right is a typical RC circuit that will discharge when the switch is closed. Which of the following would make such a circuit discharge more quickly? a. Decreasing R b. Decreasing C c. All the above d. None of the above 2. In a typical cell membrane, the phospholipid bilayer acts like a parallel plate capacitor. What part of the cell anatomy acts like a conductive wire with variable resistance? a. The ion channels b. The Na/K pump c. The cytoplasm d. The dissolved ions e. None of the above 3. A 1࠵?࠵? green laser with wavelength 550࠵?࠵? shines for 1 second. How much energy was in this pulse? a. 3 × 10 !"# ࠵? b. 1 × 10 !$ ࠵? c. 1000࠵? d. It’s impossible to tell without knowing how many photons there are. 4. A 1࠵? laser pulse made up of green photons with wavelength 550࠵?࠵? is shone. How many photons are in the pule? a. 1.3 × 10 "% b. 2.8 × 10 "& c. 5.6 × 10 ’( d. 6.0 × 10 ’$ 5. In the visible spectrum, red light has the largest wavelength and violet has the shortest. Which color has the largest energy photons? a. Red b. Orange c. Yellow d. Blue e. Violet

NAME:______________________________________________________________________ Final Exam Page 4 6. You rub a piece of glass with wool and find that it has accumulated a charge. When you bring the piece of glass near a neutral piece of Styrofoam, a. The Styrofoam is not affected because it is neutral. b. The Styrofoam is attracted to the glass. c. The Styrofoam is repelled by the glass. 7. You rub a piece of plastic with some cloth and find that it has accumulated a charge. When you bring the piece of plastic near a neutral metal sphere that is suspended by insulating string, a. The metal is not affected because it is neutral b. The metal is attracted to the plastic. c. The metal is repelled by the plastic. 8. Two identical charges are brought a distance of ࠵? = 1࠵? apart and experience a repulsive electrostatic force of ࠵? = 9 × 10 !% ࠵? . What is the magnitude of one of the charges in microcoulombs ( 1࠵?࠵? = 10 !) ࠵? )? a. 0.001࠵?࠵? b. 0.01࠵?࠵? c. 0.1࠵?࠵? d. 1࠵?࠵? e. 10࠵?࠵? 9. If two charges attract each other with a force of magnitude ࠵? when separated by a distance ࠵? , how far apart should they be to attract each other with a force of magnitude ࠵?/16 ? a. ࠵?/16 b. ࠵?/4 c. 4࠵? d. 16࠵? 10. Given two charges, one with charge ࠵? " = 1࠵? , the other with charge ࠵? ’ = 4࠵? , which feels a larger force of repulsion from the other? a. ࠵? " b. ࠵? ’ c. They both feel the same force. d. Not enough information to tell. 11. What type of charge/charges is/are likely creating the electric field pictured to the right? a. A single negative charge in the center b. A single positive charge in the center c. An electric diple d. A symmetric ring of positive charges

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