PHY112 Final Exam with Complete Questions and Answers 100% Assured Success, Exams of Physics

Download PHY112 Final Exam with Complete Questions and Answers 100% Assured Success and more Exams Physics in PDF only on Docsity! PHY112 Final Exam with Complete Questions and Answers 100% Assured Success A series R-L-C circuit with a sinusoidal voltage source of angular frequency ω has a total reactance X. If the frequency is doubled, the reactance becomes - Correct Answer none of these. A series R-L-C circuit has a sinusoidal voltage source of angular frequency ω. If the frequency is doubled - Correct Answer the inductive reactance is doubled. For the current to have its maximum value in a series R-L-C circuit, - Correct Answer ω = 1/(√LC). In a series R-L-C circuit at resonance, - Correct Answer the total impedance has its minimum value, which is equal to R. A circuit has a resistance of 4.0Ω; a reactance, due to the capacitance, of 26Ω; and a reactance, due to the inductance, of 17Ω. Find the impedance of the circuit. - Correct Answer 9.8 Ω Imp = Z The inductor in a radio receiver carries a current of amplitude 200 mA when a voltage of amplitude 2.4 V is across it at a frequency of 1400 Hz. What is the value of the inductance? - Correct Answer 1.36 mH w = 2pi(f) L = V/iw = V/I(2pi(f)) VL = IXL = 2pi(F)(I) A series circuit has a 50-Hz AC source, a 60-ohm resistor, a 0.50-H inductor, and a 10-μF capacitor. The RMS current in the circuit is 2.2 A. The power factor of the circuit is closest to - Correct Answer 0.35. P = cos(phi) = R/Z w = 2piF Find w Find XL, XC tan^-1 (X/R) = phi cos phi = P Which of the phasor diagrams shown below represents a series RLC circuit driven at resonance? http://qm.riosalado.edu/Resources/phy/phy112/20140505/Quiz5_Q8.png.JPG - Correct Answer 3 A series ac circuit is shown below. The inductor has a reactance of 70 ohms and an inductance of 210 mH. A 30-ohm resistor and a capacitor whose reactance is 120 ohms are also in the circuit. The RMS current in the circuit is 2.0 A. The peak magnetic energy in the inductor is closest to http://qm.riosalado.edu/Resources/phy/phy112/20140505/Quiz5_Q9.png - Correct Answer 0.84 J. Emax = 1/2(L)(Imax^2) Imax = sqrt(2)(I) A series ac circuit is shown below. The inductor has a reactance of 50 ohms and an inductance of 240 mH. A 50-ohm resistor and a capacitor whose reactance is 140 ohms are also in the circuit. The RMS current in the circuit is 1.2 A. The capacitor is changed so that the circuit is in resonance. The voltage of the source is adjusted so that the RMS current of 1.2 A is maintained. The new voltage amplitude of the source is closest to http://qm.riosalado.edu/Resources/phy/phy112/20140505/Quiz5_Q10.png - Correct Answer 85 V V = IZ Find Z Divide Z by sqrt(2) Multiply by I Unpolarized light with an original intensity Io passes through two ideal polarizers having their polarizing axes turned at 120° to each other. After passing through the polarizers, the intensity of the light is - Correct Answer 1/8 Io. First filter = 1/2 of light Second = cos^2(theta) Intensity = first*second If a sinusoidal wave with intensity 10 W/m2 has an electric field of amplitude E, then a 20 W/m2 wave of the same wavelength will have an electric field of amplitude - Correct Answer √2E. Two lasers each produce 2 mW beams. The beam of laser B is wider, having twice the cross-sectional area as the beam of laser A. Which of the following statements concerning the beams is (are) accurate? - Correct Answer a. Both of the beams have the same average power. b. Beam A has twice the intensity of beam B. A camera is focusing on an animal. As the animal moves closer to the lens, what must be done to keep the animal in focus? - Correct Answer The lens must be moved farther from the film (or light sensors for a digital camera). A lens of focal length 45 mm is mounted on a 35-mm camera. The lens aperture is set at f/2 and the shutter speed set at 1/2000 s. The aperture diameter, in mm, is closest to - Correct Answer 23. Aperture diameter = F/2 = 45/2 A lens of focal length 45 mm is used as a magnifier. The object being viewed is 6.8 mm long, and is positioned at the focal point of the lens. The lens is moved closer to the object, so that the image is now 25 cm from the lens. The distance the lens has been moved, in cm, is closest to - Correct Answer 0.69. 1/f = 1/do + 1/di d = f - do find do (1/f = 1/do + di) subtract do from f *convert to same units Light of wavelength λ and frequency f passes through a single slit of width a. The diffraction pattern is observed on a screen a distance x away from the slit. Which of the following will decrease the width of the central maximum? - Correct Answer c. Decrease the wavelength of the light d. Decrease the distance x of the screen from the slit. At most, how many bright fringes can be formed on one side of the central bright fringe (not counting the central bright fringe) when light of 625 nm falls on a double slit whose spacing is 6.77E-6 m? - Correct Answer 10 (e+d)sin(theta) = nlambda A pair of narrow slits, separated by 1.8 mm, is illuminated by a monochromatic light source. Light waves arrive at the two slits in phase. A fringe pattern is observed on a screen 4.8 m from the slits. If there are 5.0 bright fringes/cm on the screen, the wavelength of the monochromic light is closest to: - Correct Answer 750 nm. lambda = Ay/nd A = slit separation Y = fringe separation n = # of frings d = distance of slit to screen A pair of narrow slits, separated by 1.8 mm, is illuminated by a monochromatic light source. Light waves arrive at the two slits in phase. A fringe pattern is observed on a screen 4.8 m from the slits. Monochromic light of wavelength 450 nm is used to illuminate the screen. The angular separation between adjacent fringes on the screen, measured in mrad, is closest to - Correct Answer 0.25. y/L = (m*lambda)/d m = 1 An oil film (n = 1.48) of thickness 290 nm floating on water is illuminated with white light at normal incidence. What is the wavelength of the dominant color in the reflected light? - Correct Answer Yellow (572 nm) 2nt = (m+1/2)lambda lambda = (2nt)/(m+1/2) An 18-mm-wide diffraction grating has rulings of 710 lines per mm. Light is incident normally on the grating. Monochromatic light of 506 nm wavelength is used. The largest angle from the normal at which an intensity maximum is formed is closest to - Correct Answer 46°. sin(theta) = m(lambda)(N) m >= 1 The spacing of ruled lines on a diffraction grating is 1770 nm. The grating is illuminated at normal incidence with a parallel beam of white light in the 400 nm to 700 nm wavelength band. The longest wavelength that appears in the third order spectrum is closest to - Correct Answer 590 nm. "apply 1" = (m*lamda)/d d = m*lambda A camera used for aerial surveillance has a lens with a 30-cm maximum aperture and a 42-cm focal length. Assume light of 550 nm wavelength is used and that the resolution of the camera is limited solely by diffraction. The angular resolution of the camera at maximum aperture, in µrad, is closest to - Correct Answer 2.2. ang resolution = (F0*Amax)/lambda A rocket is traveling at (1/3)c relative to Earth when a lightbulb in the center of a cubical room is suddenly turned on. An astronaut at rest in the rocket and a person at rest on Earth both observe the light hit opposite walls of the room. Call these Events A and B. Which statement (statements) is (are) accurate concerning the observation? http://qm.riosalado.edu/Resources/phy/phy112/20140505/Quiz7_Q1.png - Correct Answer B) To the astronaut in the rocket, both events happen at the same time. C) To the observer on Earth, Event B happens before Event A. A square measuring 1 m by 1 m is moving away from Observer A along a direction parallel to one of the sides at a speed such that ϒ (defined above) is equal to 2. The area of the square measured by Observer A is - Correct Answer ½ m^2. L = L0sqrt(1-(v^2/c^2) == L0/y == L0/2 To the observer moving along with the square in Question 2 above, the time interval between consecutive blinks of her eyes is 1.0 s. To the stationary Observer A, this time interval is - Correct Answer 2 s. t = y*t0 t = 2(1) If you were in a spaceship traveling at a speed close to the speed of light (with respect to Earth) you would notice that - Correct Answer none of these effects occur. An electron has a kinetic energy equal to twice its rest energy. The speed of the electron is closest to - Correct Answer 0.94 c. E = 1/2mc^2 Light falling on a metal surface causes electrons to be emitted from the metal by the photoelectric effect. As the frequency of the light increases (everything else remains the same), which of the following statements is accurate? - Correct Answer The maximum speed of the emitted electrons increases. Consider a hypothetical single-electron Bohr atom for which an electron in the n = 1 shell has a total energy of -81.0 eV. An electron in the n = 3 shell has a total energy of -9.00 eV. Which of the statements below is/are accurate? - Correct Answer If an electron makes a transition from the n = 3 to the n = 1 shell, it will give up 72.0 eV of energy. If the Bohr radius of the n = 3 state of a hydrogen atom is R, then the radius of the ground state is - Correct Answer R/9. Radius of ground state = R/n^2 Which of the following is NOT a characteristic of laser light? - Correct Answer Laser light contains a very broad spectrum of wavelengths.