EP2 Final
What would happen to the separation between maxima if the intensity of green light increased by ×10? A.Nothing B.It would increase C.It would decrease D.The pattern would disappear
A. Nothing
Dielectric filling in the capacitor A.Reduces the electric field in the capacitor B.Increases the electric field in the capacitor C.Inserted to protect the capacitor from the discharge D.Neither of the above
A. Reduces the electric field in the capacitor
When you shine a laser on a air-water boundary, the incident and reflected angles are always A.The same B.Different, can be determined from Snell's law: n1sinθ1 = n2sinθ2 C.Different, but the relation between these two angles is too complex to be studied in EP2
A. The same
Suppose a dust cloud over our heads has acquired a negative charge via friction and is drifting from east to west. Which way will the magnetic force act on the dust cloud? A.Up B.Down C.North D.South
A. Up
If E = 0 everywhere on the surface, does that mean that there can be no charge within the surface? A.Yes B.No
A. Yes
What is the field in the center of the uniformly charged sphere of radius R with a total charge Q? A.Zero B.kQ/R^2 directed radially outwards C.kQ/R^2 directed radially inwards D.No one really knows
A. Zero
Work function of a metal A.A function that describes how well this particular metal can do useful work B.A minimum thermodynamic work (energy) needed to remove an electron from metal to a point in the vacuum outside the solid surface C.A minimum thermodynamic work (energy) needed to put an electron into the metal from the vacuum immediately outside of the solid surface
B.
Light bulbs are sold by their power consumption. How much current does the 60 W light bulb shown below draw when operating at V = 120V? A.0.2 A B.0.5 A C.1 A D.2 A
B. .5 A
What is the maximum kinetic energy for an electron liberated from a metallic surface with φ = 2.5 eV using violet light with λ = 380 nm -Reminder: KEe = hf - φ, λ = 1234 nm/E(in eV) A.0 eV (no photoelectric effect possible) B.0.7 eV C.1.4 eV D.2.5 eV
B. 0.7 ev
A magnitude of electric field from a point-like charge falls down with distance as A.1/r B.1/r^2 C.1/r^3 D.1/r^489
B. 1/r^2
An uncharged capacitor is connected through a 1 kΩ resistor to a 6V battery. The capacitor acquires a 4V difference across its terminals in 10 seconds. What is its capacitance? A.10 F B.10 mF C.10 μF D.10 nF
B. 10 mF
In an electromagnetic wave, the direction of magnetic and electric field are always at A.45 degrees B.90 degrees C.120 degrees D.0 degrees E.any angle that is constant with time and depends on how the wave was produced
B. 90 degrees
The voltage in a standard power outlet in your apartment/house is 120 V of A.Direct Current (DC) B.Alternating Current (AC)
B. AC
We perceive Ifor sound wave as volume. What do we perceive I for light waves? A.Color B.Brightness C.Opacity D.Shininess
B. Brightness
Which is the most important reason? A.Fiber optics dissipate less power B.Fiber optics carry more information C.Fiber optics are harder to "tap" D.Fiber optics are lighter E.All of the above
B. Carry more information
To maximize capacitance of two capacitors you need to A.Connect them in series B.Connect them in parallel C.Do something else, but not sure what since I have not read the textbook
B. Connect them in parallel
The security mirrors in the stores are usually A.Concave B.Convex C.Planar
B. Convex
Potential times charge has units of A.Field strength B.Energy C.Momentum D.Electric charge E.Swiss currency
B. Energy
To see better tiny details on a small object it is best to A.Bring it as close as possible to the eye without touching it B.Get a lens with positive focal distance, say f = 5 cm and look at the object through the lens C.Get a lens with negative focal distance, say f = -5 cm and look at the object through the lens D.Delegate this task to your graduate student and ask to provide a written report describing tiny details on a small object with plots, abstract, and summary
B. Get a lens with a positive focal lens
You have plugged an unknown circuit into a AC voltage supply with a variable frequency. You noticed that the current drops as you increase the frequency. The circuit reactant is mostly A.Resistive B.Inductive C.Capacitive
B. Inductive
If your RLC circuit has negligible resistance R and you plug this circuit to an AC power supply, the maximal value of the resonant voltage in the circuit will be A.Voltage of the power supply B.Infinity (or whatever maximal voltage can go through the circuit before it fries) C.Zero - you cannot have a resonance without a resistor R in RLC circuit.
B. Infinity
What would happen to the separation between maxima if the light were switched from green to red? A.Nothing B.It would increase C.It would decrease D.The pattern would disappear
B. It would increase
The power is A.A rate of current transfer (units A/s) B.A rate of energy transfer (units J/s) C.A rate of voltage transfer (units V/s) D.None of the above
B. J/s
If the flux through a closed surface is zero, does that mean E = 0 on the surface? A.Yes B.No
B. No
Which quantity is adjusted by our eyes to produce a sharp focus of an image on the retina? A.Image distance B.Radii of lens C.Object distance D.Pupil diameter
B. Radii of lens
What signal transmission property makes fiber optics the winner A.Signal propagation speed B.Signal frequency C.Signal polarization D.Signal amplitude
B. Signal frequency
Diverging lens can make A.Real images B.Virtual images C.Can do both real and virtual images
B. Virtual
A charged particle with a velocity v perpendicular to the magnetic field B will travel in a A.Straight line B.Ellipse C.Rectangular path D.Circle E.Ferrari
D. Circle
Which of the following is NOT a type of magnetism? A.Ferromagnetism B.Diamagnetism C.Paramagnetism D.Exomagnetism
D. Exomagnetism
When you see yourself in a mirror, your image is A.Real and inverted B.Real and upright C.Imaginary and inverted D.Imaginary and upright
D. Imaginary and upright
What would happen to the separation between maxima if the red light only came through the top slit and green light only through the bottom slit? A.Nothing B.It would increase C.It would decrease D.The pattern would disappear
D. The pattern would disappear
The reason there are two slits, rather than one, in a Young's experiment is A.One slit is for electric field, while the other is for magnetic field B.To increase the intensity C.Two slits in parallel offer less resistance D.To create a path length difference E.One slit is for frequency, the other for wavelength
D. create a path length difference
How many protons are needed for 1 C of charge? A.1.6×10-19 B.1 C.6.2×1018 D.6.0×1025
C. 6.2x10^18
A myopic eye focuses a distant object to a point in front of, not on, the retina. What kind of sense can be used to correct for myopia? A.A bi-convex lens B.A converging lens C.A negative focal length lens
C. A negative focal length lens
For calculation of magnetic field from a generic current (no obvious symmetry) we should use A.Coulomb's law B.Ampere's law C.Biot-Savart's law D.Murphy's law
C. Biot-Savart's Law
Photoelectric effect is A.A conspiracy theory, does not really exists but invented by psychotic scientists to distress undergraduate students before finals B.Emission of photons when you hit some material with high energy electrons C.Emission of electrons when you hit some material with high energy photons
C. Emission of electrons
A chunk of iron is a good example of which material? A.Diamagnet B.Paramagnet C.Ferromagnet
C. Ferromagnet
Inductor is a device that A.can produce known electric and magnetic field in a specified region B.can produce known electric field in a specified region C.can produce known magnetic field in a specified region
C. can produce a magnetic field
Which statement is most correct? A.Inductors are short circuits at low frequencies and open circuits at high frequencies B.Inductors are short circuits at high frequencies and open circuits at low frequencies C.Inductors are short circuits at low and high frequencies D.Inductors are open circuits at low and high frequencies
A
If you are 5'6'' tall and you stand 4' in front of a mirror, how tall does the mirror have to be for you to see your entire body? A.2'9'' B.4' C.5'6'' D.8'
A. 2'9"
We perceive f for sound wave as pitch. What do we perceive f for light waves? A.Color B.Brightness C.Opacity D.Shininess
A. Color
Which quantity is adjusted for a camera to produce a sharp focus of an image on the film or CCD/CMOS sensor plane? A.Image distance B.Radii of lens C.Object distance D.Pupil diameter
A. Image distance
A fuse is a piece of conductor designed to run up and break when the current through it exceeds some rated value. To protect a circuit, it should be wired A.In series with the rest of the circuit B.In parallel with the rest of the circuit C.Does not matter, it protects the circuit no matter where it is connected
A. In series
To calculate magnetic flux used in Faraday's law of induction A.you integrate over a volume B.you integrate around the closed loop C.you integrate over a surface
C. integrate over a surface
What is the resistance of the 60W light bulb when operating at V = 120V? A.60 Ω B.120 Ω C.240 Ω D.480 Ω
C.240 Ω
Interference of light is evidence that A.Light is electromagnetic in character B.The speed of light is very large C.light does not obey conservation of energy D.light is a wave phenomenon E.light is a transverse wave
D. light wave phenomenon
What would happen to the real image in the previous slide if you blocked off the lower half of a converging lens? A.The entire image would disappear B.The upper half of the image would disappear C.The lower half of the image would disappear D.The image would remain, albeit dimmer
D. the image would remain
A charged capacitor consists of two isolated conductors with A.Two charges, same in magnitude, opposite in sign B.Two charges, same in magnitude, same in sign C.Two charges, could be differentin magnitude, but must be samein sign D.Two charges, could be differentin magnitude, must be of differentsign
A
An electric dipole consists of A.Two charges of equal magnitude but opposite signs separated by a small distance B.Two charges of equal magnitude and equal signs separated by a small distance C.Any number of charges of equal magnitude D.Any number of charges with any magnitude
A
Gauss' law relates A.The electric field at points on a closed Gaussian surface to the net charge enclosed by that surface B.The electric field at points on an open Gaussian surface to the net charge on that surface C.The electric field at infinity due to charges on Gaussian surface
A
Inside a long solenoid the magnetic field A.Pretty much uniform inside, and almost no magnetic field outside B.Very strong inside and outside C.Very strong in the center, but very weak close to the coils and outside
A
Resistance is A.A property of a conductor that relates a potential difference on the conductor and a current that flows through it B.A property of a conductor that shows the maximal current that current cannot exceed C.Futile
A
The direction of the current is chosen as A.the direction of where positive charges would flow B.the direction of where negative charges would flow C.arbitrarily, on a case by case basis
A
To increase the magnetic field inside the solenoid you can A.Increase the current and number of turns B.Increase the current only - number of turns just make the field uniform C.Increase the number of turns - current strength has little or no effect
A
When charging the capacitor with an EMF A.Initially current is large, but then it gets smaller as the capacitor gets more and more charged. Initially voltage on a capacitor is small, but then it gets larger until it matches the one of EMF B.Initially current is small, but then it gets larger as the capacitor gets more charged. Initially the voltage on a capacitor is the same as EMF, but as capacitor gets charged it gets very small C.Both current and voltage are very small, but then they get larger as the capacitor is charged
A
What is the maximum kinetic energy for an electron liberated from a metallic surface with φ = 2.5 eV using red light with λ = 650 nm -Reminder: KEe = hf - φ, λ = 1234 nm/E(in eV) A.0 eV (no photoelectric effect possible) B.0.7 eV C.1.4 eV D.2.5 eV
A. 0 ev
An EMF device A.does work on charges by maintaining constant potential difference across its terminals B.does work on electric field to keep the charges flowing across terminals C.is an idealized (perfect) battery
A.
Most electronics devices work over a certain range of loads. In the drawing below, a gadget with an effective resistance Rload is plugged into the voltage divider. Pick the condition below that assures the voltage divider will work as intended? A.Rload≫ R2 B.Rload≪ R2 C.Rload≈ R2
A.
What is a plausible value of the resistance of a multimeter operating as an ammeter and how should a multi-meter be connected to measure a current through a resistor? A.RAM = 10-3Ω; connect in series with resistor B.RAM = 10+7Ω; connect in series with resistor C.RAM = 10-3Ω; connect in parallel with resistor D.RAM = 10+7Ω; connect in parallel with resistor
A.
Unpolarized light passes through a single polarizer with an intensity of 1.00 mW/m2. It then passes through a second polarizer that has its transmission axis aligned at 45 degrees with that of the first polarizer, and then a third polarizer with its axis aligned at 135 degrees relative to the first. What is the intensity of the light upon exiting this polarizer? A.0.00 mW/m2 B.0.25 mW/m2 C.0.50 mW/m2 D.1.00 mW/m2
A. 0
Inductance is a property of an inductor that is defined as A.a ratio of a total magnetic flux in the inductor to the current that flows though the inductor B.a product of total magnetic flux in the inductor and the current that flows through it C.maximal magnetic flux that can go through the inductor without damaging it
A. the ratio of total magnetic flux to currents
To see better tiny details on a small object you chose to use a converging lens with f = 5 cm. What would be the maximal magnification of this object? Assume that you stop being able to see clearly at anything closer than 25 cm A.×6 B.×5 C.×1/6 D.×5 E.Not possible to calculate.
A. x6 (p/f +1)
Light is called polarized if A.The direction of propagation of the waves is always at 90 degrees to the directions of the electric field vectors E B.The direction of the electric field vectors E of the waves are always in the same plane C.The direction of the magnetic field vectors B is at 90 degrees to the direction of the electric field vectors E of the waves
B.
Converging lens can make A.Real images B.Virtual images C.Can do both real or virtual images
C. both
At least two transformers operate between us in Manhattan and the Jeffrey Energy Center in Bellevue, where our electric power originates. What kind of transformers are these? A.Jeffrey: step-up. Manhattan: step-up B.Jeffrey: step-up. Manhattan: step-down C.Jeffrey: step-down. Manhattan: step-up D.Jeffrey: step-down. Manhattan: step-down
B
Electric potential at a point P in the electric field is A.The work that would be needed to bring a positive test charge from infinity to the point P, divided by the charge itself B.Negative of what is written above C.Is the same as an electric field at point P but times the charge value D.Is the same as an electric field at point P but divided by the test charge value
B
If a conducting sphere is charged, the excess charge will be A.Uniformly distributed throughout the volume of the sphere B.Uniformly distributed on the surface of the sphere C.Found at random places due to Gauss law
B
Magnetic field lines A.Just like electric field lines - they start at north pole and move towards south pole where they terminate B.Unlike electric field lines - form loops that pass through north and south pole.
B
Notice that the electroscope will indicate charge even if the rod is brought near, but not touching the top knob. A positive charge on the rod pulls negative charge to the knob, leaving the needles and support positively charged. What happens to the needle when the rod is removed? A.It does not move and remains deflected B.It returns to its un-deflected position and stays there C.It returns to its un-deflected position, and then deflects again D.It explodes with a loud bang destroying both electroscope and the instructor
B
The electric flux Φ through a surface is A.Amount of Coulomb's force on this surface B.Amount of electric field that pierces the surface C.Amount of Coulomb's force that pierces the surface
B
The north pole is actually A.North magnetic pole of the planet B.South magnetic pole of the planet C.I do not want to vote on this one
B
When discharging a capacitor with a screwdriver a la Prof. Maravin A.Initially, the current through the screwdriver and potential difference on the terminals of the capacitor are small, but increase as the capacitor gets discharged B.Initially, the current through the screwdriver and potential difference on the terminals of the capacitor are large, but decrease as the capacitor gets discharged C.The current decreases, but the voltage stays the same, provided the screwdriver is in good contact with terminals of the capacitor
B
Which statement is most correct? A.Capacitors are short circuits at low frequencies and open circuits at high frequencies B.Capacitors are short circuits at high frequencies and open circuits at low frequencies C.Capacitors are short circuits at low and high frequencies D.Capacitors are open circuits at low and high frequencies
B
If you connect a fully charged capacitor to the inductor, what willhappen? A.The capacitor quickly gets dischargedthrough the inductor and neither currentacross inductor nor charge will be found on the capacitor B.The capacitor will get discharged and then recharged again to a different polarity, then discharged through the inductor and re-charged again, and so on ad infinitum. C.The capacitor will never get discharged as the inductor will resist any current to flow through it.
B.
Kirchhoff's rules are A.Essentially the same as Smirnoff's rules but more applied for electrical circuits without FPGAs and other complex integrated circuits B.Used to "solve" electrical circuits (determine currents, potential differences etc.) C.Simple rules to ensure safety and correct operation of the circuit (for example - ensure that batteries are plugged with right polarity etc.)
B.
Magnetic field in the toroid A.Is uniform inside and very weak outside B.Is not uniform inside and very weak outside C.Is weak inside, but very strong in the center of the loop that forms a toroid
B.
Magnetic field from the long straight wire A.Falls in magnitude with distance as 1/r^2 B.Falls in magnitude with distance as 1/r C.Is constant, just like the electric field from an infinite charged sheet D.Increases with distance as r
B. falls as 1/r
A 1 mF capacitor discharges 66% of its charge through a resistor in 1 second. What is the resistance? A.1 Ω B.10 Ω C.1000 Ω D.10000 Ω
C
For an electrically charged particle to experience force from a magnetic field... A.Cannot happen, electrically charged particles experience force from electric field, you need magnetic charges to feel a force from the magnetic field B.the particle must not be at rest C.the particle must not be at rest and must have a non-zero perpendicular projection of the velocity to the magnetic field
C
In mechanical engineering and electrical engineering applications resonance conditions are usually A.ME: bad, EE: bad B.ME: good, EE: bad C.ME: bad, EE: good D.ME: good, EE: good
C
A resonance in a circuit is a phenomena that happens when A.You connect a circuit to a DC power supply with the voltage matching the "natural" voltage of the circuit B.You connect a circuit to an AC power supply with the current matching the "natural" current of the circuit C.You connect a circuit to an AC power supply with the frequency matching the "natural" frequency of the circuit
C.
Junction rule is A.Currents in circuit always flow through junctions B.Currents that flow to junctions always flow according to right hand rule C.Sum of currents that enter a junction must be equal to the sum of currents that leave this junction
C.
Magnetic field lines from the long straight wire A.Is radially outwards from the wire (if current is positive) B.Is radially inwards from the wire (if current is positive) C.Form concentric circles around the wire
C.
Unpolarized light passes through a single polarizer with an intensity of 1.00 mW/m2. It then passes through a second polarizer that has its transmission axis aligned with that of the first polarizer. What is the intensity of the light upon exiting this polarizer? A.0.00 mW/m2 B.0.25 mW/m2 C.0.50 mW/m2 D.1.00 mW/m2
C. 0.5
Unpolarized light passes through a single polarizer with an intensity of 1.00 mW/m2. What is the intensity of the light upon exiting the polarizer? A.0.00 mW/m2 B.0.25 mW/m2 C.0.50 mW/m2 D.1.00 mW/m2
C. 0.5
If we generate charge separation (or polarization) by bringing the positive rod close to the electroscope and then touch the needle section, the positive charge on the needle will be grounded out, but the negative charge on the knob will be held in place by the charged rod •If we remove our hand from the needle and then pull the rod away from the knob, what will be the charge on the electroscope? A.Positive B.Zero C.Negative
C. Negative
A plane mirror has m = 1. Does it do anything to the object? A.It blows up its size B.It inverts C.It switches right with left D.The image is an exact copy of the object
C. Switches left and right
Which quantity or quantities take on the same value on all points of a good conductor? A.Surface charge density B.Normal component of electric field C.Voltage D.A and B E.B and C
C. Voltage
What is a plausible value of the resistance of a multimeter operating as a voltage meter and how should a multi-meter be connected to measure voltage across a resistor? A.RVM = 10-3Ω; connect in series with resistor B.RVM = 10+7Ω; connect in series with resistor C.RVM = 10-3Ω; connect in parallel with resistor D.RVM = 10+7Ω; connect in parallel with resistor
D.
What is the worst mistake you can make in connecting a meter to a "load resistor"? A.Putting a volt-meter in series with the load B.Putting an ammeter in series with the load C.Putting a volt-meter in parallel with the load D.Putting an ammeter in parallel with the load
D.
How long would it take for a magnet to slide down a conducting pipe? A.< 1 sec B.2 sec C.3 sec D.5 sec E.> 5 sec
E. >5sec
Copper cables are being ripped up everywhere in the world and replaced with fiber optics for signal transmission applications. Why? A.Fiber optics dissipate less power B.Fiber optics carry more information C.Fiber optics are harder to "tap" D.Fiber optics are lighter E.All of the above
E. All of the above
How can we get more maximum voltage from a rotating coil generator? A.Increase the field B.Increase the number of turns C.Wrap the coils around iron D.Spin the coils faster E.All the above works!
E. All the above
1 cm2 area. Coil 2 carries 1 A of current in 2 loops around a 2 cm2 area. How large will coil 2's field B2 be compared to coil 1's field B1 at a distance of 1 m from the center of either coil? A.B2/B1 = 1/4 B.B2/B1 = 1/2 C.B2/B1 = 1 D.B2/B1 = 2 E.B2/B1 = 4
E. B2/B1 = 4
Coulomb's law describes the force between two electrically charged particles A. True B. False
True
Electric charge can be positive or negative A.True B.False
True
