Physics 222 Spring 2009 Final Exam Version B (870862)

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1 Physics 222 Spring 2009 Final Exam Version B (870862) Question Instructions Be sure to answer every question. Follow the rules shown on the first page for filling in the Scantron form. Each problem is worth 10% of the exam. When you are finished, check with Dr. Mike or his TA to be sure you have finished the scantron correctly. 1. Question DetailsElectric Potential (1) [ ] A charge of 7 nc is placed at the orgin. A second - 22 nc charge is placed on the x-axis 3 m to the right of the origin. What is the potential at a point on the x-axis 10 m to the left of the origin? z*01*10.65 V x*04*1.20 V w*06*21.51 V y*05*-0.54 V v*10*-8.92 V The potential for each point charge is given by the equation. V = k q / r Note that this is a scalar and thus we do NOT take the absolute value of the charge. For the first charge we have a distance of 10 m between the charge and where the potential is measured. For the second charge that distance is 13 m. Thus, V 1 = 6.29 V and V 2 = V. We then just add these together. 2. Question DetailsWhat do we see? (3) [ ] (For this problem, ignore the top blank box in the figure.) What would the box containing the letters A and B look like to the eye in the figure? (Be careful. The answers may not be in order from I to IV.)

2 z*00*none of these w*05*figure II x*03*figure III v*10*figure I

3 y*03*figure IV Trace a ray from the left and right side of the A, as well as from the left and right side of the B, and you will see that the mirror image of a mirror image looks just like the object. By the way, I was able to find at least one ray from every point on the A and B that hit the eye. 3. Question DetailsComplex Circuits (2) [ ] What is the equivalent resistance for the circuit below? (If it helps, assume that there is a battery attached between points A and B.) v*10*17.5 ohms x*07*72 ohms y*01*110 ohms z*01*70 ohms w*03*48.75 ohms The 20Ω and the 30Ω resitors in the upper-right of the diagram are in parallel. Their equivalent resistance is R eq = 1 / (1/20Ω + 1/30Ω) = 12Ω. This equivalent resistor would then be in series with the remaining 30Ω resistor in the top of the figure to give us R eq =30Ω + 12Ω = 42Ω. Finally, this is in parallel with the bottom 30Ω resistor. To give us the final answer R eq = 1 / (1/42Ω + 1/30Ω) = 17.5Ω. 4. Question DetailsPhotoelectric Effect (3) [ ] Using the numbers in the figure below, determine λ for v max = 8.15 x 10 5 m/s?

4 y*03*481 nm x*01*1019 nm v*10*319 nm w*00*1140 nm z*05*150 nm The kinetic energy of the photon is K = 1/2 m v 2 And, the photoelectric equation tells us that E = K max + W 0, where W 0 = 2eV. The freqency of the light is then f = E/h. and the wavelength is given by λ = c / f. 5. Question DetailsCutoff Frequency (3) [ ] The cutoff frequency of a given material is 5.3 x Hz, what is its work function? v*10*2.20 ev z*01*0.83 ev y*03*0.33 ev w*00*0.96 ev x*04*3.51 ev The cutoff energy is E cutoff = h f cutoff

5 which gives us a work function of W o = E cutoff. 6. Question DetailsCharge (1) [ ] Which of the following is NOT found in a typical atom. v*10*top quark x*01*electron y*05*down quark z*01*they are all found there. w*05*up quark The protons and neutrons are made of up and down quarks. The electron is also found in the atom. So, that leaves us with a top quark, which can only be found in a laboratory or in exotic situations in space. 7. Question DetailsInterference (1) [ ] For the figure below, if the fringes shown are the zeroth and 7 th order fringes, what is the slit separation? It is s in the figure, but in our notes it is d w*03*2.20 mm y*01*8.80 mm z*01*11.00 mm v*10*15.40 mm x*01*6.60 mm For this case, 1.3 mm / 5.2 m = tanθ and d = 7 (550 nm) / sinθ.

8. Question DetailsWave Particle Duality (2) [1110501] Wave-particle duality tells us that... v*10*light has properties of both a wave and a particle.

6 8. Question DetailsWave Particle Duality (2) [ ] Wave-particle duality tells us that... v*10*light has properties of both a wave and a particle. x*02*light is a lot of particles called photons that oscillate to make a wave. w*07*light is sometimes a wave and sometimes a particle. z*01*interference and the photoelectric effect are actually the same thing. y*02*light is a wave that is confined to a single point which we call a photon. Like a gumball has properties of both a marble and candy at the same time, so light has the properties of BOTH waves and particles AT THE SAME TIME! 9. Question DetailsElectric Field Lines (3) [ ] Which of the following is true about the charges q A for particle A and q B for particle B in the figure below? x*07*q A = 32 and q B = -4 w*06*q A = + 4 q B z*01*nothing can be said about them without more information. y*03*q A = -32 and q B = 4 v*10*q A = - 4 q B A has four times as many field lines as B and the field lines point out of A and into B. Note that A is a positive charge and B is a negative charge. 10. Question DetailsMagnetic Field (3) [ ] What is the direction of the magnetic field in each section of the figure?

7 v*10*1 toward you, 2 away from you, 3 away from you, 4 toward you x*04*1 up, 2 left, 3 down, 4 left y*03*1 left, 2 up, 3 left, 4 down w*07*1 away from you, 2 toward you, 3 toward you, 4 away from you z*01*none of these. Using the right hand, we point our fingers in the direction of the initial velocity (left, up, left, down) and curl them in the direction of the magnetic field (toward you, away from you, away from you, toward you). Our thumb then points in the direction of the force or acceleration (up, left, down, left). Assignment Details Name (AID): Physics 222 Spring 2009 Final Exam Version B (870862) Submissions Allowed: 100 Category: Exam Code: Locked: No Author: DeAntonio, Michael ( mdeanton@nmsu.edu ) Last Saved: May 4, :20 PM MDT Permission: Protected Randomization: Person Which graded: Last Feedback Settings Before due date Nothing After due date Nothing

Physics 212 Spring 2009 Exam 2 Version C (832725)

Physics 212 Spring 2009 Exam 2 Version C (832725) Question 1 2 3 4 5 6 7 8 9 10 Instructions Be sure to answer every question. Follow the rules shown on the first page for filling in the Scantron form.