Physics 2 Final

When two point charges are a distance d part, the electric force that each one feels from the other has magnitude F. In order to make this force twice as strong, the distance would have to be changed to

d/√2

After being cut in half in Part A, the organ pipe is closed off at one end. What is the new fundamental frequency?

f0

Two speakers face each other, and they each emit a sound of wavelength λ. One speaker is 180∘ out of phase with respect to the other. If we separate the speakers by a distance 1.5λ, how far from the left-most speaker should we place a microphone in order to pick up the loudest sound? Ignore reflections from nearby surfaces. Select all that apply.

lambda, 0 lambda, 1/2 lambda

Two in-phase speakers 2.0 m apart in a plane are emitting 1800 Hz sound waves into a room where the speed of sound is 340 m/s. The point 4.0 m in front of one of the speakers, perpendicular to the plane of the speakers, a point of maximum constructive interference, perfect destructive interference, or something in between?

perfect destructive interference

Is Φsquare larger than, smaller than, or equal to Φcircle?

Φsquare>Φcircle

The current through a wire is measured as the potential difference Δ V is varied. What is the wire's resistance?

0.02 Ohm

For charged particles, what is the quantity q/m called?

Charge-to-mass ratio

What is the SI unit of charge?

Coulomb

Suppose you have two point charges of opposite sign. As you move them farther and farther apart, the potential energy of this system relative to infinity

Increases

Is the proton's speed v2 at point 2 larger than, smaller than, or equal to v3?

v2=v3

Is ΔU1→2, the change in potential energy along the path 1→2, larger than, smaller than, or equal to ΔU1→3?

ΔU1→2=ΔU1→3

Suppose that we repeat the experiment shown in the video, but we replace one of the cylinders with a cylinder that has twice the radius (and use larger containers of water). If the height of the original cylinder is h, how deeply must we submerge the new cylinder to get the same weight reduction as in the video?

(1/4)h

If three uncharged styrofoam balls are placed together and agitated so that one gains +3 C of charge and another gains +4 C of charge, how much charge must there be on the third one?

+ 7 C

When two point charges are 2.0 cm apart, each one experiences a 1.0-N electric force due to the other charge. If they are moved to a new separation of 8.0 cm, the electric force on each of them is closest to

0.063 N

Wire 2 is twice the length and twice the diameter of wire 1. What is the ratio R2 / R1 of their resistances?

1/2

Two conducting spheres are each given a charge Q. The radius of the larger sphere is three times greater than that of the smaller sphere. If the electric field just outside of the smaller sphere is E0, then the electric field just outside of the larger sphere is

1/9 E0

Every minute, 120 C of charge flow through this cross section of the wire. The wire's current is...

2A

Consider a pipe of length L that is open at both ends. What are the wavelengths of the three lowest-pitch tones produced by this pipe?

2L, L, 2L/3

A capacitor is connected to a 9 V battery and acquires a charge Q. What is the charge on the capacitor if it is connected instead to an 18 V battery?

2Q

If the spacing between the plates in capacitor 1 is d, what should the spacing between the plates in capacitor 2 be to make the capacitance of the two capacitors equal?

2d

If the organ pipe is cut in half, what is the new fundamental frequency?

2f0

The air from the pipe in Part B (i.e., the original pipe after being cut in half and closed off at one end) is replaced with helium. (The speed of sound in helium is about three times faster than in air.). What is the approximate new fundamental frequency?

3f0

A tube open at one end and closed at the other end produces sound having a fundamental frequency of 350 Hz. If you now open the closed end, the fundamental frequency becomes

700 Hz

What device provides a practical way to produce a uniform electric field?

A parallel-plate capacitor

The electric field of a charge is defined by the force on what kind of particle?

A probe charge

A small object is released in the center of the capacitor in the figure(Figure 1) . For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A negative object is released from rest.

Accelerates to the left.

A small object is released in the center of the capacitor in the figure(Figure 1) . For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A positive object is released from rest.

Accelerates to the right.

Maxwell introduced the displacement current as a correction to

Ampère's law.

In a resonating pipe that is open at both ends, there

Are displacement antinodes at each end.

All other things being equal, current will be larger in a wire that has a larger value of

Conductivity

Consider an air-filled charged capacitor. How can its capacitance be increased?

Decrease the spacing between the plates of the capacitor.

Suppose you have two negative point charges. As you move them farther and farther apart, the potential energy of this system relative to infinity

Decreases

Consider a charged parallel-plate capacitor. How can its capacitance be halved?

Double the plate separation or halve the plate area.

Which of the following would double the amount of current flowing through a piece of metal wire?

Double the voltage across it.

Two large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half way between the two plates the electric field has magnitude E. If the separation of the plates is reduced to d/2 what is the magnitude of the electric field half way between the plates?

E

A rod attracts a positively charged hanging ball. The rod is

Either negative or neutral

A charge alters the space around it. What is this alteration of space called?

Electric Field

What is the amount of electric field passing through a surface called?

Electric Flux

If the resistivity of copper is less than that of gold at room temperature, which of the following statements must be true?

Electrons in gold are more likely to be scattered than electrons in copper at room temperature when they are accelerated by the same electric field.

A proton and an electron are released from rest in the center of a capacitor. Is the force ratio Fp/Fe greater than 1, less than 1, or equal to 1?

Equal to one

A 6.00-cm-diameter sphere with a mass of 89.3 g is neutrally buoyant in a liquid. What is the liquid?

Ethyl alcohol

A point charge Q is located a short distance from a point charge 3Q, and no other charges are present. If the electrical force on Q is F, what is the electrical force on 3Q?

F

If the electric flux through a closed surface is zero, the electric field at points on that surface must be zero.

False

When the electric field is zero at a point, the potential must also be zero there.

False

What is the SI unit of capacitance?

Farad

What is the relationship between gauge pressure and true pressure?

Gauge pressure is smaller than true pressure.

Consider a charged parallel-plate capacitor. Which combination of changes would quadruple its capacitance?

Halve the plate separation and double the plate area.

The electric potential inside a capacitor.

Increases linearly from the negative to the positive plate.

In a resonating pipe that is open at one end and closed at the other end, there

Is a displacement node at the closed end and a displacement antinode at the open end.

The electric field

Is always perpendicular to the equipotential surface.

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

Is always perpendicular to the surface of the conductor

As in the video, we apply a charge +Q to the half-shell that carries the electroscope. This time, we also apply a charge -Q to the other half-shell. When we bring the two halves together, we observe that the electroscope discharges, just as in the video. What does the electroscope needle do when you separate the two half-shells again?

It does not deflect at all

A certain sound is recorded by a microphone. The same microphone then detects a second sound, which is identical to the first one except that it has twice the frequency. In addition to the higher frequency, what distinguishes the second sound from the first one?

It is perceived as higher in pitch.

A certain sound is recorded by a microphone. The same microphone then detects a second sound, which is identical to the first one except that the amplitude of the pressure fluctuations is larger. In addition to the larger amplitude, what distinguishes the second sound from the first one?

It is perceived as louder.

At the same temperature, two wires made of pure copper have different resistances. The same voltage is applied at the ends of each wire. The wires may differ in

Length, cross-sectional area, amount of electric current passing through them.

A proton and an electron are released from rest in the center of a capacitor. Is the acceleration ratio ap/ae greater than 1, less than 1, or equal to 1?

Less than one

The law that characterizes polarizers is called

Malus's law.

An electromagnetic wave is propagating in the positive x direction. At a given moment in time, the magnetic field at the origin points in the positive y direction. In what direction does the electric field at the origin point at that same moment?(Figure 1)

Negative Z

A negative charge is moved from point A to point B along an equipotential surface. Which of the following statements must be true for this case?

No work is required to move the negative charge from point A to point B.

There are some points on a standing wave that never move. What are these points called?

Nodes

The various possible standing waves on a string are called the

Normal modes

The equation I = Δ V/R is called

Ohm's Law

Two blocks are of identical size. One is made of lead and sits on the bottom of a pond; the other is made of wood and floats on top. On which is the buoyant force greater?

On the lead block (because the buoyant force is proportional to the immersed volume of the liquid so, because the lead block is completely immersed, the buoyant force on the lead block is greater)

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.

What is the SI unit of pressure?

Pascal

Having established that a sound wave corresponds to pressure fluctuations in the medium, what can you conclude about the direction in which such pressure fluctuations travel?

Pressure fluctuations travel along the direction of propagation of the sound wave.

What is a sound wave?

Propagation of pressure fluctuations in a medium

Rank the following types of electromagnetic waves by the wavelength of the wave. Rank the wavelength of the electromagnetic waves, in order from longest to shortest. If the wavelength is the same, place them on top of each other.

Radio waves, microwaves, visible light, x-rays

A small object is released in the center of the capacitor in the figure(Figure 1) . For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A neutral but polarizable object is released from rest.

Remains in place.

What property of objects is best measured by their capacitance?

The ability to store charge

At a certain depth in the ocean, the absolute pressure is p. If you go to twice that depth (treating the water as incompressible)

The absolute pressure will be less than 2p.

At a given location in space, the magnetic field in an electromagnetic wave is increasing. How is the electric field changing at that same location?

The electric field is increasing.

Four +2 μC charges are placed at the positions (10 cm, 0 cm), (−10 cm, 0 cm), (0 cm, 10 cm), and (0 cm, −10 cm) such that they form a diamond shape centered on the origin. A charge of +5 μC is placed at the origin. If the force between a +2 μC and a +5 μC charge separated by 10 cm has a magnitude of 9 N, which of the following can we say about the force on the +5 μC charge at the origin in this case?

The force of the charge at the origin is 0.

The figure shows the electromagnetic field as a function of position for two electromagnetic waves traveling in a vacuum at a given moment. Which statement about the frequency and speed of the waves is correct?(Figure 2)

The frequency of wave A is greater than that of wave B, but the speeds of the two waves are the same.

A 50-cm3 block of wood is floating partially submerged in water, and a 50-cm3 block of iron is totally submerged in water. Which block has the greater buoyant force on it?

The iron

The buoyant force on an object submerged in a liquid depends on

The object's volume and density of the liquid.

A parallel-plate capacitor is connected to a battery. After it becomes charged, the capacitor is disconnected from the battery and the plate separation is increased. What happens to the potential difference between the plates?

The potential difference between the plates increases

If a negatively charged rod is held near a neutral metal ball, the ball is attracted to the rod. This happens because

The rod polarizes the metal

When a wave pulse on a string reflects from a boundary, how is the reflected pulse related to the incident pulse?

The shape is inverted, but the amplitude is unchanged

What happens to the tension in the string if the Ping-Pong ball is replaced by a smaller spherical object of equal weight?

The tension decreases.

Salt is now added to the water in the bucket, increasing the density of the liquid. What happens to the tension in the string ?

The tension of the string increases.

How do the resistances of two conducting wires compare if they have the same length, but one is twice the radius of the other?

The thicker wire has one-fourth the resistance of the thinner wire.

You are holding a positive charge and there are positive charges of equal magnitude 1 m to your north and 1 m to your east. What is the direction of the force on the charge you are holding?

To the southwest.

If the electrical potential in a region is constant, the electric field must be zero everywhere in that region.

True

If the spacing between the plates, d, is the same in both capacitors, and the voltage across capacitor 1 is V, what is the voltage across capacitor 2?

V/2

What are the units of potential difference?

Volts

The electric field inside a conductor in electrostatic equilibrium is

Zero