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PHYS 204 Final Exam All Possible
Questions with Answers.
If you increase the diameter of a loop of wire, what will happen to the strength of the induced magnetic field? a) Increase b) Decrease c) Not affected - Correct Ans: ✔✔b) Decrease The magnetic field induced in a single loop of wire is B = 3 T. If the same wire is looped 3 times into a coil, what will the magnetic field of the coil be? a) 3 T b) 1 T c) 9 T d) 6 T - Correct Ans: ✔✔c) 9 T What is the magnetic field, B, induced in a single loop of wire with a radius of 0.5m by a 2A current? - Correct Ans: ✔✔ 8 πx10-7 T In the lab, when we change the number of loops in the tangent galvanometer coil, what do we expect to happen? a) The radius of the coil changes.
b) The direction of the current changes. c) The deflection angle changes. d) The permeability changes. - Correct Ans: ✔✔c) The deflection angle changes. If you move the switch from one side to the other of a double-pole- double-throw switch (going past the middle), which statement best describes what happens in the circuit? a) The power goes from on to off. b) The current reverses direction everywhere in the circuit. c) The ammeter switches from reading positive to negative current. d) The current in one loop of the circuit reverses in direction. - Correct Ans: ✔✔d) The current in one loop of the circuit reverses in direction. How should the plane of the coil of a tangent galvanometer by positioned to measure the Earth's magnetic field? - Correct Ans: ✔✔Vertical in the magnetic North-South direction What happens to the compass needle when the current is turned on in the tangent galvanometer? - Correct Ans: ✔✔It moves by some amount depending on the strength of the current.
The speed of light in a vacuum is c = 3x10-8 m/s. Glass has an index of refraction of n = 1.5. What is the speed of light in glass? a) less than c b) greater than c c) c d) not enough information - Correct Ans: ✔✔a) less than c What happens when light passes from a medium with a lower index of refraction to a medium with a higher index of refraction, for example from n1 = 1.0 to n2 = 1.5? a) The light is not bent. b) The angle to the normal gets smaller. c) The angle to the normal gets bigger. d) The light is always bent at 45 degrees. - Correct Ans: ✔✔b) The angle to the normal gets smaller. When an object is reflected in a plane mirror, how does the image distance, q, related to the object distance, p? a) They are always the same except in different directions. b) p is always more than q c) p is always less than q
d) p and q both depend on the angles of incidence and reflection so are not directly related - Correct Ans: ✔✔a) They are always the same except in different directions. A ray of light is incident on a flat mirror with an incident angle of 60 degrees. What is the reflected angle? - Correct Ans: ✔✔60 degrees. Why does the path of light change when it travels from air to clear glass? a) All the light waves bounce off the surface fo the glass. b) The speed of light is slower in glass. c) The light bends away from the normal. d) The wavelength of the light changes. - Correct Ans: ✔✔b) The speed of light is slower in glass. A pin is placed 7cm in front of the plane mirror. Where is the image of the pin? - Correct Ans: ✔✔7cm behind the mirror Which of the following describes a spherical convex thin lens? a) the thickness is about equal to the diameter b) can focus parallel light rays to a single point c) two surfaces curve inward d) the focal length varies depending on object distance - Correct Ans: ✔✔b) can focus parallel light rays to a single point
d) the distance between the test lens and the original object. - Correct Ans: ✔✔c) The distance between the test lens and the virtual object. What is the spherical aberration (SA) of a lens where light passing through the edges of the lens has a focal point of 5cm and light passing through the center has a focal point of 7cm? - Correct Ans: ✔✔SA = 2 After light passes through a diffraction grating, places where the crests meet up create ______________ spots called ___________. - Correct Ans: ✔✔bright, maxima A diffraction grating consists of: a) many slits etched into a plastic surface b) a special polarizing plastic c) a double slit apparatus d) a single slit - Correct Ans: ✔✔a) many slits etched into a plastic surface When light passes through a diffraction grating, the angle at which the light is diffracted depends on _________________. - Correct Ans: ✔✔the wavelength of the light When an electron drops down to a lower energy level in an atom, what happens? - Correct Ans: ✔✔light is emitted
Which of the following statements best defines spectrum? a) all the colors of the rainbow b) individual photons of light c) light separated by intensity d) light separated by wavelength - Correct Ans: ✔✔d) light separated by wavelength Some properties of stars are determined by observing ______________ line __________ spectra. - Correct Ans: ✔✔dark, absorption What is the purpose of the green and red lasers in the spectroscopy experiment? a) to provide light with known wavelengths as a reference/calibration b) the diffraction grating requires a laser to function properly c) to mark where bright emission lines should occur d) the lasers are just an additional data point - Correct Ans: ✔✔a) to provide light with known wavelengths as a reference/calibration Which gas should have more emission lines: Helium or Hydrogen? - Correct Ans: ✔✔Helium What is an application of a Wheatstone bridge?
d) Ra < Rb - Correct Ans: ✔✔b) Rx > R According to the junction rule for the Wheatstone bridge, which of these must be true? (reference picture of Wheatstone bridge in lab manual) a) Ig = Ia + Ib b) Ix = I + Ig c) I = Ia + Ib d) Ib = Ig + Ia - Correct Ans: ✔✔d) Ib = Ig + Ia If you increase the length of a wire in the Wheatstone bridge, what happens to the resistance? a) decreases b) increases c) it remains the same d) it depends on the resisitivity - Correct Ans: ✔✔b) increases You have two wires, both are the same length and same diameter. However, one is copper wire (p = 1.7E-8 Ωm) and the other is nickel- silver wire (p = 28E-8. Ωm). Which wire has the greater resistance? - Correct Ans: ✔✔Nickel-silver wire For the Wheatstone bridge, what element has the unknown resistance?
a) a slidewire b) a resistor c) a galvanometer d) a spool of wire - Correct Ans: ✔✔d) a spool of wire What does it say when the Wheatstone bridge is balanced? a) There is no current running through the slide-wire. b) The current running through the top of the bridge is equal to the current in the bottom (I = Ia). c) There is no current running through the top of the bridge (R and Ra). d) There is no current running through the middle (Ig = 0). - Correct Ans: ✔✔d) There is no current running through the middle (Ig = 0). A balanced slide-wire Wheatstone bridge has the following properties: La = 40cm, Lb = 60cm, and R = 20Ω. What is the unknown resistance, Rx? (refer to lab manual for equation)
- Correct Ans: ✔✔Rx = 30Ω In the Tangent Galvanometer lab, what were we trying to measure? - Correct Ans: ✔✔The Earth's magnetic field A coil of wire is laid flat on a table. A current is passed through the wire in a clockwise direction. What is the direction of the induced magnetic field?
