PHY 232 Final

A 1.4-cm-tall candle flame is 55 cm from a lens with a focal length of 19 cm. What is the image distance? Test 4

di = 29 cm

The figure shows a snapshot of a traveling wave at t=0 moving at a speed of v= 18.0 m/s. What is the frequency of the traveling wave in the figure? Test 1

f = 1.50 Hz

A French submarine and a U.S. submarine move toward each other during maneuvers in motionless water in the North Atlantic. The French sub moves at 44.00 km/h, and the U.S. sub at 61.00 km/h. The French sub sends out a sonar signal (sound wave in water) at 1000 Hz. Sonar waves travel at 5470 km/h . What is the signal's frequency as detected by the U.S. sub? Test 1

f = 1019 Hz

A series LRC circuit consists of a 100 Ω resistor, a 47.3 μF capacitor and a 3.00 mH inductor connected across a 120 VV rms ac voltage source operating at 100 Hz. At what frequency will this circuit be in resonance? Test 4

f = 423 Hz

In a series LRC circuit, the frequency at which the circuit is at resonance is f0. If you double the resistance, the inductance, the capacitance, and the voltage amplitude of the ac source, what is the new resonance frequency?

f0/2

In the figure, two solenoids are moving away from each other. The induced current through the resistor R is

from b to a

When a thin film of liquid spreads out and floats on water, the thinnest part looks dark. The index of refraction of the liquid is

higher than water

A transverse wave traveling along a string transports energy at a rate r. If we want to double this rate, we could

increase the amplitude by a factor of sqrt(2)

Under electrostatic conditions, the electric field just outside the surface of any charged conductor

is always perpendicular to the surface of the conductor

The "guide star" at the Very Large Telescope (VLT)

is the fake star that the sodium laser cast in the sky to "untwinkle" the stars in view.

Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in same directions. Both wires carry current toward you. From your point of view, the magnetic field at the point exactly midway between the two wires

is zero

When light goes from one material into another material having a HIGHER index of refraction

its speed and wavelength decrease, but its frequency stays the same.

In a double-slit experiment that uses monochromatic light, the angular separation between the central maximum and the second-order maximum is 0.900 ∘. What is the wavelength of the light if the distance between the slits is 0.300 mm? Test 4

lambda = 2.36*10^-6 m

A ray of light is traveling in a glass cube that is totally immersed in water. You find that if the ray is incident on the glass-water interface at an angle to the normal greater than 50.8 ∘, no light is refracted into the water. Use 1.33 for the index of refraction of water. What is the refractive index of the glass? Test 4

n = 1.72

Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on the left carries current toward you. From your point of view, the magnetic field at the point exactly midway between the two wires

points upward

How far from the center of a wire carrying a 4.90 A current does the magnetic field that results from the current have a magnitude of 4.00×10^−4 T? Test 3

r = 2.45 mm

An object is 30 cm in front of a converging lens of focal length 10 cm. The image is:

real and smaller than the object

A concave mirror has a 38 cm radius of curvature. How far from the mirror must an object be placed to create an upright image three times the height of the object?

s = 13 cm

An AC current is flowing through the primary of a transformer, and the magnitude of the current as a function of time is shown in the figure. At which moment in time is the induced EMF across the secondary of the transformer a maximum?

t2

When the frequency of the oscillator in a series RLC circuit is halved:

the capacitive reactance is doubled

An air-filled parallel-plate capacitor is connected to a battery and allowed to charge up. Now a slab of dielectric material is placed between the plates of the capacitor while the capacitor is still connected to the battery. After this is done, we find that

the charge on the capacitor had increased.

Consider an LRC circuit that is driven by an AC applied voltage. At resonance,

the current is in phase with the driving voltage.

Ampère's law is often written integral ∮B→(r→)⋅dl→=μ0Iencl. The integral on the left is

the line integral along the closed loop.

A slit of width 0.13 mm is illuminated with monochromatic light of wavelength 632.8 nm. At what angle will the third order minimum occur? Test 4

theta = 0.84 degrees

Fiber optics depends upon the phenomenon of

total internal reflection.

A 0.299 m -long bar moves on parallel rails that are connected through a 6.19 Ω resistor, as shown in the following figure, so the apparatus makes a complete circuit. You can ignore the resistance of the bar and rails. The circuit is in a uniform magnetic field 1.23 T that is directed into the plane of the figure. At an instant when the induced current in the circuit is counterclockwise and equal to 1.69 A, what is the magnitude of the velocity of the bar? Test 3

v = 28.4 m/s

A 1.20-m long gas column that is open at one end and closed at the other end has a fundamental resonant frequency 80.0 Hz. What is the speed of sound in this gas? Test 1

v = 384 m/s

A standing wave is oscillating at 200 Hz on a string, as shown in the figure. What is the speed of traveling waves on this string? string length = 60cm Test 1

v = 80 m/s

A 4.8×10−4 V/m electric field creates a 2.7×10^17 electrons/s current in a 1.8-mm-diameter aluminum wire. The electron density of aluminium is 6.0×10^28/m3. What is the drift speed? Test 2

vd = 1.8*10^-6 m/s

A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. (a) At the moment contact is made with the battery the voltage across the capacitor is

zero

In a LRC circuit, the rms voltages Vab= 16 V, Vbc= 21 V and Vcd= 21 V. What is the input voltage ξ?

16 V

If the sound level is increased by -41.0 dB the intensity changes by a factor of: Test 1

7.94*10^-5

An object is 15 cm in front of a concave mirror with a focal length of 21 cm . Locate the image. Test 4

di = -53 cm

A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is

open at one end and closed at the other end.

A charge is accelerated from rest through a potential difference V and then enters a uniform magnetic field oriented perpendicular to its path. The field deflects the particle into a circular arc of radius R. If the accelerating potential is tripled to 3V, what will be the radius of the circular arc?

(√3)*R

An electron with an initial speed of 4.60×105 m/s is brought to rest by an electric field. The mass of an electron is 9.1×10−31kg and its charge is 1.6×10−19C. What was the potential difference that stopped the electron? Test 2

-0.602 V

An electron moving in the direction of the x -axis enters a magnetic field. If the electron experiences a magnetic deflection in the −y direction, the direction of the magnetic field in this region points in the direction of the

-z-axis

An inductor is connected in series with a resistor as shown in the circuit below. The switch was first at position b. The switch is then being thrown to position a. After a long time, the voltage drop across the inductor will be

0

A very long, solid, conducting cylinder of radius R carries a current along its length uniformly distributed throughout the cylinder. Which one of the graphs shown in the figure most accurately describes the magnitude B of the magnetic field produced by this current as a function of the distance r from the central axis?

1 (straight line up, curved line down)

A certain Energy Star qualified cooktop is rated at 1100 W. This cook top can be plugged into a regular 120 V/15A outlet. What is the resistance of this cook top? Test 2

13.1 ohms

The original carbon arc lamp has electrodes made of pure carbon (resistivity of 3.5×10−5Ωm). What is the resistance of a 12.6 mm -diameter, 8.00 cm-long carbon electrode? Test 2

2.25×10^−2 Ω

A cylindrical wire has a resistance R and resistivity ρ. If its length and diameter are BOTH cut in half, what will be its resistance?

2R

Which one of the phasor diagrams shown below best represents a series LRC circuit driven at resonance?

3

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the wavelength of the wave.

3.0 m

An electric field E =6.00×105i N/C causes the point charge in the figure to hang at an angle. What is θ? Test 1

37 degrees

A square current loop 4.60 cm on each side carries a 550 mA current. The loop is in a 0.900 TT uniform magnetic field. The axis of the loop, which is perpendicular to the plane of the loop, is 24.0 ∘ away from the field direction. What is the magnitude of the torque on the current loop? Test 3

4.26 *10^-4 N*m

A resistor is made out of a long wire having a length L. Each end of the wire is attached to a terminal of a battery providing a constant voltage V0. A current III flows through the wire. If the wire were cut in half, making two wires of length L/2, and both wires were attached to the battery (the end of both wires attached to one terminal, and the other ends attached to the other terminal), what would be the total current flowing through the two wires?

4I

A violin string is 21.0 cm long. It sounds the musical note A (440 Hz) when played without fingering. How far from the end of the string should you place your finger to play the E note (659 Hz)? Test 1

6.98 cm

The displacement of a wave traveling in the negative y-direction is D(y,t) = ( 5.70 cm ) sin ( 6.20 y+ 61.0 t ), where y is in m and t is in s. Test 1

9.84 m/s

When two or more capacitors are connected in series across a potential difference

All of the above choices are correct.

A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?

As it moves farther and farther from QQQ, its speed will keep increasing.

A certain commercial mass spectrometer is used to separate uranium ions of mass 3.92×10−25 kg and charge 3.20×10−19 C from related species. The ions are accelerated through a potential difference of 100 kV and then pass into a uniform magnetic field, where they are bent in a path of radius 0.680 mm . After traveling through 180° and passing through a slit of width 1.00 mm and height 1.00 cm, they are collected in a cup. What is the magnitude of the (perpendicular) magnetic field, B, in the separator? Test 3

B = 0.728 T

A wire bent into the shape shown below. The diameter of the circular portion of the wire is d= 2.50 cm . A current of I= 2.45 AA runs through the wire. Calculate the magnitude of the magnetic field at the center of the loop in the figure ? Test 3

B = 1.62 * 10^-4 T

A parallel-plate capacitor consists of two parallel, square plates that have dimensions 1.0 cm by 1.0 cm. If the plates are separated by 4 mm, and the space between them is filled with teflon, what is the capacitance of this capacitor? (The dielectric constant for teflon is 2.1, and ε0 = 8.85 × 10-12 C2/N · m2.) Test 2

C = 0.460 pF

A copper penny slides on a horizontal frictionless table. There is a square region of constant uniform magnetic field perpendicular to the table, as shown. Which graph correctly shows the speed v of the penny as a function of time t?

D (looks like going downstairs)

A person can see clearly up close, but cannot focus on objects beyond 90.0 cm. She opts for contact lenses to correct her vision. Test 4

D = -1.11 diopters

Four traveling waves are described by the following equations, where all quantities are measured in SI units and y represents the displacement. I: y = 0.12 cos(3x + 2t) II: y = 0.15 sin(6x - 3t) III: y = 0.23 cos(3x + 6t) IV: y = -0.29 sin(1.5x - t) Which of these waves have the same speed?

D: I and IV

A ten-loop coil having an area 0.69 m^2 and a very large resistance is in a 4.8×10^−2 T uniform magnetic field oriented so that the maximum flux goes through the coil. The coil is then rotated so that the flux through it goes to zero in 0.44 s . What is the magnitude of the average emf induced in the coil during the 0.44 s? Test 3

E = 0.753 V

What is the minimum magnitude of an electric field that balances the weight of a plastic sphere of mass 5.1 g that has been charged to -3.0 nC? Assume that only electric field balances gravity. Test 1

E = 1.7*10^7 N/C

The electric field between square the plates of a parallel-plate capacitor has magnitude E. The potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. The magnitude of the electric field between the plates is now equal to

E/2

The cube in the figure has edge length 1.40 m and is oriented as shown in a region of uniform electric field. Find the electric flux through face (3) if the electric field, in newtons per coulomb is given by E→= -3.80i N/C + -2j N/C. Test 1

Electric Flux = 0 Nm^2/C

Two very large parallel sheets a distance d apart have their centers directly opposite each other. The sheets carry equal but opposite uniform surface charge densities. A point charge that is placed near the middle of the sheets a distance d/2 from each of them feels an electrical force F due to the sheets. If this charge is now moved closer to one of the sheets so that it is a distance d/4 from that sheet, what force will feel?

F

A particle with charge -4 C initially moves at v = (1.00 i + 7.00 j ) m/s. If it encounters a magnetic field B = 90 T k, find the magnetic force vector on the particle. Test 3

F = -2520, 360 N

A very long straight wire carries a 20.0 A current eastward and a second very long straight wire carries a 20.0 A current westward. The wires are parallel to each other and are 42.0 cm apart. Calculate the force on a 6.40-m length of one of the wires. Test 3

F =1.22×10^−3 N

In the figure, the inner loop carries a counter-clockwise current I that is increasing. The resistor R is in the outer loop and both loops are in the same plane. The induced current through the resistor R is

From b to a

An LRC circuit has a sinusoidal voltage supplied to it at 197 kHz with a peak voltage of 270 V; a 20.0 kΩkΩ resistance; a 70 μF capacitance; and a 67.0 mH inductance. What is the peak current for this circuit?

I = 3.16 mA

Three polarizing filters are stacked, with the polarizing axis of the second and third filters at angles of 18.0 ∘ and 57.6 ∘, respectively, to that of the first. If unpolarized light is incident on the stack, the light has an intensity of 74.5 W/cm2 after it passes through the stack. If the incident intensity is kept constant, what is the intensity of the light after it has passed through the stack if the second polarizer is removed? TEST 4

I = 39.8 W/cm²

A 0.55 μF capacitor is connected across an AC generator that produces a peak voltage of 12 V. What is the peak current to and from the capacitor if the emf frequency is 100 kHz? Test 4

IC = 4.0 A

A 22.0 mH inductor is connected across an AC generator that produces a peak voltage of 9.00 V. What is the peak current through the inductor if the emf frequency is 100 kHz? Test 4

IL = 6.5*10^-4 A

Which statements are true for an electron moving in the direction of an electric field? (There may be more than one correct choice.)

Its electric potential energy increases as it goes from high to low potential. Its potential energy increases as its kinetic energy decreases. Its kinetic energy decreases as it moves in the direction of the electric field.

An organ pipe open at both ends has two successive harmonics with frequencies of 400 Hz and 450 Hz . What is the length of the pipe? The speed of sound at the time is 341 m/s . Test 1

L = 3.41 m

You are given two converging lenses to build a compound microscope. Lens A has focal length 0.50 cm and lens B has focal length of 3.0 cm. Which of the two lenses would you use for the objective?

Lens A, because it has the shorter focal length.

Suppose that you wish to construct a simple ac generator having an output of 12.0 V maximum when rotated at 60.0 Hz . A uniform magnetic field of 8.00×10−2 T is available. If the area of the rotating coil is 199 cm^2 , how many turns do you need? Test 3

N = 20 turns

Assume all angles to be exact. In a particular diffraction grating pattern, the red component (700 nm) in the third-order maximum is deviated at an angle of 26 ∘. How many lines per centimeter does the grating have? Test 4

N = 2090 lines/cm

A transformer changes the 10.0 kV power line to 120 V. If the primary coil contains 1500 turns, how many turns are on the secondary? Test 3

Ns = 18 turns

The heater element of a particular 120-V toaster is a 8.9-m length of nichrome wire, whose diameter is 0.47 mm. The resistivity of nichrome at the operating temperature of the toaster is 1.3 × 10-6 Ω · m. If the toaster is operated at a voltage of 120 V, how much power does it draw? Test 2

P = 220 W

The four identical capacitors in the circuit shown in the figure are initially uncharged. Let the charges on the capacitors be Q 1, QQQ 2, Q 3, and Q 4 and the potential differences across them be V 1, V 2, V 3, and V 4. The switch is thrown first to position A and kept there for a long time. It is then thrown to position B. Which of the following conditions is true with the switch in position B?

Q1 = 3*Q2

What resistance should be added in series with a 0.750 H inductor to complete an LR circuit with a time constant of 3.00 ms? Test 3

R = 250 ohms

What is the equivalent resistance between points aa and bb in the figure where R1= 360 Ω, R2= 550 Ω, R3= 550 Ω and R4= 510 Ω. Test 2

Rab = 292 ohms

A light bulb is connected in the circuit shown in the figure with the switch S open. All the connecting leads have no appreciable resistance and the battery has no internal resistance. When we close the switch, which statements below accurately describe the behavior of the circuit? (There may be more than one correct choice.)

The brightness of the bulb will increase The potential drop across R2 will decrease.

A bar magnet is held vertically with its upper end a little bit below the center of a horizontal metal ring. The upper end of the magnet is its north pole, as shown in the figure. The bar magnet is now dropped An observer views the ring from above its center. To this observer, how will the induced current in the ring behave?

The current will flow counter-clockwise and be decreasing.

The figure shows a steady electric current passing through a wire with a narrow region. What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?

The drift velocity increases from A to B and decreases from B to C.

In a double-slit experiment, if the slit separation is decreased, which of the following happens to the interference pattern shown on the screen?

The maxima get further apart.

Suppose a region of space has a uniform electric field, directed towards the right, as shown in the figure. Which statement about the electric potential is true?

The potential at points A and B are equal, and the potential at point C is lower than the potential at point A.

A wave pulse traveling to the right along a thin cord reaches a discontinuity where the rope becomes thicker and heavier. What is the orientation of the reflected and transmitted pulses?

The reflected pulse returns inverted while the transmitted pulse is right side up.

Why is the variable inductor not be replaced by a variable resistor?

The resistor will also dissipate energy which is undesirable.

Which one of the following statements is true?

The sound intensity can never be negative, but the intensity level (in dB) can be negative.

A 7.00-μF parallel-plate capacitor has charges of 50.0 μC on its plates. How much potential energy is stored in this capacitor? Test 2

U = 179 microJ

A 3 μF capacitor has a potential difference of 5 V applied across its plates. If the potential difference across its plates is increased to 8 V, how much ADDITIONAL energy does the capacitor store? Test 2

U = 59.0 microJ

A 4.00 mH inductor and a 8.10 Ω resister are wired in series to a 12.0 V ideal battery. A switch in the circuit is closed at time 0, at which time the current is zero. Calculate the energy stored in the inductor 7 ms later. Test 3

U =4.39×10^−3 J

The capacitive network shown in the figure is assembled with initially uncharged capacitors. A potential difference, Vab = +100V, is applied across the network. The switch S in the network is kept open. Assume that all the capacitances shown are accurate to two significant figures. What is potential difference Vcd across the open switch S? Test 2

V = 40.0 V

In a LRC circuit, the rms voltages Vab= 16 V, Vbc= 15 V and Vcd= 16 V. What is the value of the voltage Vac? Test 4

Vac = 21.9 V

In an L-R-C series circuit, the resistance is 500 ohms, the inductance is 0.400 henrys, and the capacitance is 2.00×10−2 microfarads. The capacitor can withstand a peak voltage of 580 volts. If the voltage source operates at the resonance frequency, what maximum voltage amplitude Vmax can the source have if the maximum capacitor voltage is not exceeded? Test 4

Vmax = 64.8 V

A vertical wire carries a current straight up. To the west of this wire, the magnetic field points in which direction?

West

Which one of the following is an accurate statement about light?

When light strikes a surface at Brewster's angle, only the reflected light is 100% polarized.

The Young's modulus of aluminum can be found in this demonstration in our lecture. A sound sensor is held near the end of an aluminum rod. The rod is held at the midpoint with both ends of the rod free to move. One end of the rod is given a sharp strike. The rod begins to ring at some particular frequencies and picked up by the sound sensor which is connected to the computer. The speed of sound traveling in a solid can be expressed as v=√(Y/ρ), where v is the speed of sound in the solid, Y is the Young's modulus and ρ is the density of the solid. The resonance frequency is picked up by a spectrum analyzer and the length of the rod measured. Assuming that the predominant mode of vibration of the rod is in its fundamental frequency, we can then find the speed of sound in the solid using our simple standing wave equation. In one demonstration, the density of the rod was first measured using Archimedes Principle and the value of the density was found to be 2,700 kg/m3. The rod was then held in the middle and struck at one end. The frequency was analyzed. If the length of the rod is measured to be 1.30 m and the fundamental frequency from the spectrum analyzer is 1923 Hz . What is the Young's modulus of Aluminium? Test 1

Y = 6.8*10^10 Pa

A circuit has a resistance of 14 Ω; a reactance, due to the capacitance, of 71 Ω and a reactance, due to the inductance, of 29 Ω. Find the impedance of the circuit. Test 4

Z = 44 ohms

An ac source of period T and maximum voltage V is connected to a single unknown ideal element that is either a resistor, and inductor, or a capacitor. At time t=0 the voltage is zero and decreasing. At time t=T/4 the current in the unknown element is equal to zero, and at time t=T/2 the current is I=Imax, where Imax is the current amplitude. What is the unknown element?

a capacitor

In a diagram of electric field lines, what is represented by lines that are drawn closer together?

a stronger field

The thinnest part of a soap film

appears dark and does not reflect any light because all wavelength of light interferes destructively.