Physics 1402 Final Exam

Which of the following values can be taken by the electron spin number, ms?

+- 1/2

At a certain instant in time, the electric field of an electromagnetic wave in free space points in the -z direction, and the magnetic field points in the + y direction. In what direction is this wave traveling?

+x direction

Given that the binding energy of the hydrogen atom in its ground state is -13.6 eV, what is the energy when it is in the n=5 state?

-0.544 eV

An orbital angular momentum quantum number L can have any integer value ranging from

0 to (n-1)

A circular coil of 20 turns and radius 5.0 cm is placed with its plane oriented a 90 degrees to a uniform magnetic field of 0.10 T. The field is now increased at a steady rate, reaching a value of 0.50 T after 4.0 seconds. What emf is induced in the coil?

0.016 V

A proton having a speed of 3.0 x 10^6 m/s in a direction perpendicular to a uniform magnetic field moves in a circle of radius 0.20 m within the field. What is the magnitude of the magnetic field?

0.16 T

A pair of narrow slits that are 1.8 mm apart is illuminated by a monochromatic coherent light source. A fringe pattern is observed on a screen 4.8 m from the slits. If the wavelength of the monochromatic light is 450 nm, what is the angular separation between adjacent dark fringes on the screen, measured in miliradians?

0.25 mrad

A small 0.050-kg insulated sphere carries a charge of -60 uC and is hanging by a vertical silk thread from a fixed pint in the ceiling. An external uniform vertical electric field is now applied. If the applied electric field has a magnitude of 3000 N/C and is directed downward, what is the tension in the silk thread?

0.31 N

A 4.0 resistor is connected with a 12 resistor and this combination is connected across an ideal dc power supply with V = 6.0 V, as shown in the figure. When a total current I flows from the power supply, what is the current through the 12 resistor?

0.50 A

An object is placed 26 cm from a concave lens having a focal length of magnitude of 30 cm. What is the magnification?

0.54

A certain photon, after being scattered from a free electron that was at rest, move at an angle of 120 degrees with respect to the incident direction. If the wavelength of the incident photon is 0.591 nm what is the wavelength of the scattered photon?

0.595 nm

A spaceship traveling at 0.50c away from Earth launches a secondary rocket in the forward direction at 0.50c relative to the spaceship. As measured by Earthlings, how fast is the secondary rocket moving away from Earth?

0.80c

Which one of the following numbers is the correct magnification produced by a plane mirror

1

A rigid rectangular loop, measuring 0.30 m by 0.40 m, carries a current of 5.5 A, as shown in the figure. A uniform external magnetic field of magnitude 2.9 T in the -x direction is present. Segment CD s in the xz plane and forms a 35 degree angle with the z-axis, as shown. What is the magnitude of the torque that the magnetic field exerts on the loop?

1.1 N*m

The speed of light in a certain material is measured to be 2.2 x 10^8 m/s. What is the index of refraction of this material?

1.4

A sphere of surface area 1.25 m2 and emissivity 1.0 is at a temperature of 100 C. At what rate does it radiate heat into empty space?

1.4 kW

What is the momentum of a photon of light that has a wavelength of 480 nm?

1.4 x 10-27 kg*m/s

A beam of light, traveling in air, strikes a plate of transparent material at an angle of incidence of 56.0 degrees. it is observed that the reflected and refracted beams form an angle of 90.0 degrees. What is the index of refraction of this material?

1.48

A proton moving eastward with a velocity of 5.0 m/s enters a magnetic field of 0.20 T pointing northward. What are the magnitude and direction of the force that the magnetic field exerts on the proton?

1.6 x 10-16 N upward

How much work must we do on an electron to move it from point A, which is at a potential of +50 V, to point B, which is at a potential of -50 V, along the semicircular path shown in the figure?

1.60 x 10^-17 J

The wavelength of a ruby laser is 694.3 nm. What is the energy difference between the two energy states for the transition that produces this light?

1.79 eV

A 200-W light bulb is connected across a 110-V dc power supply. What current will flow through this bulb?

1.8 A

A pion is an unstable particle that has a mean lifetime of 2.55 x 10-8 s. This is the time interval between its creation in a nuclear process and its extinction into decay products, as measured in a frame of reference at rest with respect to the pion. An average pion is traveling at 0.230c relative to Earth. How far does it travel in its lifetime, relative to Earth.

1.81 m

The coil of an ac generator has 50 loops and a cross-sectional area of 0.25 m2. What is the maximum emf that can be generated by this generator if it is spinning with an angular speed of 4.0 rad/s in a 2.0- T magnetic field?

100 V

Coherent light of wavelength 573 nm falls on a double-slit and the third-order bright fringe is seen at an angle of 6.5 degrees away from the centerline. How far apart are the double slits?

15 um

A conducting rod whose length is l= 25 cm is place don a U shaped metal wire that is connected to a lightbulb having a resistance of 8.0 as shown in the figure. The wire and the rod are in the plane of the page. A constant uniform magnetic field strength 0.40 T is applied perpendicular to and out of the paper. An external applied force moves the rod to the left with a constant speed of 12 m/s/ What are the magnitude and direction of the induced current in the circuit?

150 mA counterclockwise

An object that is 47.5 cm tall forms as image that is 38.6 cm tall and 14.8 cm from a spherical mirror. How far is the object from the mirror?

18.2 cm

If this index of refraction of a material is 2, this means that light travels

2 times as fast in vacuum as it does in material

After a proton with an initial speed of 1.50 x 10^5 m/s has increased its speed by accelerating through a potential difference of 0.100 kV, what is its final speed?

2.04 x10^5 m/s

A point charge of +3.00 uC and a second charge Q are initially very far apart. If it takes 29.0 J of work to bring them to a final configuration in which the +3.00 uC charge is at the point x= 1.00 mm, y = 1.00 mm, and the second charge Q is at the point x = 1.00 mm, y = 3.00 mm, find the magnitude of the charge Q.

2.15 uC

What current is flowing in a wire if 0.67 C of charge pass a point in the wire in 0.30 s?

2.2 A

An ideal 100- V dc battery is applied across a series combination of four resistors having resistances of 20, 40, 60, 80. What is the potential difference across the 40 resistor?

20 V

A high power line carries a current of 1.0 kA. What is the strength of the magnetic field this line produces at the ground 10 m away?

20 uT

A beam of light in air enters a glass slab with an index of refraction of 1.40 at an angle of incidence of 30.0 degrees. What is the angle of refraction?

20.9 degrees

The primary of an ideal transformer has 100 turns and its secondary has 200 turns. If the input voltage to the primary is 100 V, we can expect the output voltage of the secondary to be

200 V

A small charged plastic ball is vertically above another charged small ball in a frictionless test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the equilibrium distance between the balls in the test tube would become

2d

In a two-slit experiment using coherent light, the distance between the slits and the screen is 1.10 m, and the distance between the slits is 0.100 mm. If the first-order bright fringe is measured to be 3.40 cm from the centerline, what is the wavelength of light?

3.09 um

A spaceship carrying a light clock moves at a speed of 0.960c relative to an observer on Earth. If the clock on the ship advances by 1.00 s as measured by the space travelers aboard the ship, how long did that advance take as measured by an observer on Earth?

3.6 s

An object that is 75 cm tall is located 3.8 m in front of a plane mirror. The image formed by the mirror appears to be

3.8 m behind the mirror's surface

An oil layer that is 5.0 cm thick is spread smoothly and evenly over the surface of water on a windless day. A light ray from the air above enters the oil at 45 degrees with the normal and then goes into the water. What is the angle of refraction of this ray in the water? The index of refraction for the oil is 1.15, and for water it is 1.33

32 degrees

What is the wavelength used by a radio station that broadcasts at a frequency of 920 kHz?

326 m

The critical angle for a substance in air is measured at 53.7 degrees. If light enters this substance from air at 45.0 degrees with the normal, at what angle with the normal will it continue to travel?

34.7 degrees

Unpolarized light passes through a combination of two ideal polarizers. The transmission axes of the first polarizer and the second polarizer are at 30.0 degrees to each other. What percentage of the original light gets through the combination

37.5%

A particle in a 799 m long linear particle accelerator is moving at 0.875c. How long doe the particle accelerator appear to the particle?

387 m

A certain electromagnetic field traveling in vacuum has a maximum electric field of 1200 V/m. What is the maximum magnetic field of this wave?

4.0 x 10-6 T

A thin copper rod 1.0 m long has a mass of 0.050 kg ad is in a magnetic field of 0.10 T. What minimum current rod is needed in order for the magnetic force to balance the weight of the rod?

4.9 A

A cell phone is placed 40 cm in front of a converging lens with a focal length of magnitude 20 cm. How far is the image of this phone from the lens

40 cm

Lucite has an index of refraction of 1.50. What is its critical angle if it is in air?

41.8 degrees

Two tiny particles having charges of +5.00 uC and +7.00 uC are placed along the x-axis. The +5.00-uC particle is at x=00.0 cm, and the other particle is at x=100 cm. Where on the x-axis must a third charged particle be placed so that it does not experience any net electrostatic force due to the other two particles?

45.8 cm

The work function of a particular metal is 4.20 x 10-19 J. What is the photoelectric cutoff (threshold) wavelength of this metal?

473 nm

How many values of the magnetic quantum number, ml are possible if the orbital angular momentum quantum number is L= 2?

5

What is the wavelength of the matter wave associated with a 0.50-kg ball moving at 25 m/s?

5.3 x 10-35 m

Two electrons are 20.0mm apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other?

5.8 x 10^-25

A certain metal wire has a cross-sectional area of 1.0 cm2 and a resistivity of 1.7 x 10-8. How long would it have to be to have a resistance of 1.0?

5.9 km

An object with a rest mass of 0.456 kg is moving at 1.20 x 10^8 m/s. What is the magnitude of its momentum?

5.97 x 10^7 kg*m/s

Light from a He-Ne laser of wavelength 633 nm passes through a circular aperture. The resulting pattern is observed on a screen 4.0 m behind the aperture, where the width of the central bright circle is 1.1 cm. What is the diameter if the hole?

560 um

A hydrogen atom is in 6h state. What is the principal quantum number?

6

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are perpendicular

6.3 x 10-3 T*m2

How many electrons are necessary to produce 1.0 C of negative charge?

6.3 x 10^18

How much energy is carried by a photon of light having frequency 110 GHz

7.3 x 10-23 J

A proton is placed in an electric field of intensity 800 N/C. What are the magnitude and direction of the acceleration of the proton due to this field?

7.66 x 10^10 m/s^2 in the direction of the electric field

At a particular point and instant, the magnetic field component of an electromagnetic wave is 15.0 uT. What is the magnetic energy density of this wave at that point and instant?

8.5 x 10-5 J/m3

A sinusoidal electromagnetic field traveling in vacuum has a maximum electric field of 1200 V/m. What is the maximum magnetic field of this wave?

85kW/m2

Two tiny beads, each of mass 3.2 g, carry equal-magnitude charges. When they are placed 6.4 cm apart and released in outer space, they begin to accelerate towards each other at 538m/s2. What is the magnitude of the charge on each bead?

890 nC

A person's face is 30 cm in front of a concave spherical shaving mirror. If the image is an erect image that is 1.5 times as large as the object, what is the focal length mirror?

90 cm

An air-filled 20-uF capacitor has a charge of 60 uC on its plates. How much energy is stored in this capacitor?

90 uJ

Which statement about a single thin lens is correct

A diverging lens always produces a virtual upright image

Three equal charges +Q are at three of the corners of a square of side d. A fourth charge +Q of equal magnitude is at the center of the square as shown in the figure. Which one of the arrows shown represents the net force acting on the charge at the center of the square?

B

Identical light bulbs can be attached to identical ideal batteries in three different ways (A, B, or C) as shown in the figure. The ranking (from lowest to highest) of the total power produced by the battery is

B, A, C

A parallel-plate capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference across the plates. A slab of dielectric material is inserted in the region between the plates and completely fills it. What changes would you observe as the dielectric is inserted?

Both the charge on the plates of the capacitor and its capacitance would change

Three equal negative point charges -q are placed at three of the corners of a square of side d as shown in the figure. Which one of the arrows shown represent the direction of the net electric field at the center of the square?

C

According to Lenz's law, the induced current in a circuit always flows to oppose the external magnetic flux through the circuit

False

If unpolarized light of intensity Io passes through an ideal polarizer, what is the intensity of the emerging light?

Io/2

As temperature of a blackbody increases, what happens to the peak wavelength of the light it radiates?

It gets shorter

As shown in the figure, a metal bar is in contact with a pair of parallel rails and is in motion with an upward velocity of magnitude v. A uniform magnetic field is present , directed downward as shown. The direction of the induced current through a resistor R is

No current induced

When an object moves close to the speed of light relative to Earth, what happens to its dimensions compared to what they were before it began moving, as measured by an Earth-based observer?

Only lengths parallel to direction of travel are decreased

Observer A sees a pendulum oscillating back and forth in a relativistic rocket and measures its period to be TA. Observer B moves along with the rocket and measures the period of the pendulum to be TB. What is true about these two time measurements?

TA>TB

Four unequal resistors are connected in series wit each other. Which one of the following statements is correct about this combination?

The equivalent resistance is more than the largest resistance

A negatively-charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two sphere are then separated, what kind of charge will be on the spheres?

The sphere near the charged rod becomes positive and the other one becomes negative

Which one of the following types of electromagnetic wave travels through space the fastest?

They all travel through space at the speed of light

The figure shows two unequal charges, +q and -Q. Charge -Q has greater magnitude than charge +q. Point X is midway between the charges. In what section of the line will there be a point where the resultant electric field is zero?

VW

In making a transition from state n=1 to state n=2, the hydrogen atom must

absorb a photon of energy 10.2 eV

Single convex spherical mirrors produce images that

are always smaller than the actual object

You are moving at a speed of 2/3c toward Randy when they sine a light towards you. At what speed do you see the light approaching you?

c

A horizontal wire carries a current straight toward you. From your point of view, the magnetic field caused by this current

circles the wire in a counter-clockwise direction

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?

current

If the maximum possible accuracy in measuring the velocity of a particle increases, the maximum possible accuracy in measuring its position will

decrease

If you were to cut a small permanent bar magnet in half,

each piece would in itself be a smaller bar magnet with both north and south poles

We observe that a moving charged particle experiences no magnetic force. From this we can definitely conclude that

either no magnetic field exists or the particle is moving parallel to the field

The energy density of an electromagnetic wave in free space is

equally divided between the magnetic and electric fields

Light enters air from water. The angle of refraction will be

greater than the angle of incidence

The index of refraction of a type of glass is 1.50, and the index of refraction of water is 1.33. If light enters water from this glass, the angle of refraction will be

greater than the angle of incidence

A positive charge is moving to the right and experiences an upward magnetic force, as shown in the figure. In which direction must the magnetic field have a component?

into the page

A plastic rod is charged up by rubbing a wool cloth, and brought to an initially neutral metallic sphere that is insulated from ground. It is allowed to touch the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod

is repelled by the sphere

In a double-slit experiment, it is observed that the distance between adjacent maxima on a remote screen is 1.0 cm What happens to the distance between adjacent maxima when the slit separation is cut in half

it increases to 2.0 cm

If the frequency of a light beam is doubled, what happens to the momentum of the photons in that beam of light?

it is doubled

If the wavelength of a photon is doubled, what happens to its energy?

it is reduced to one-half of its original value

Increasing the brightness of a beam of light without changing its color will increase

its number of photons per second traveling in the beam

You buy a AA battery in the store, and it is marked 1.5 V. If this marking is strictly accurate. while this battery is fresh

its terminal voltage will be less than 1.5 V when it is used in a circuit

Light enters glass from air. The angle of refraction will be

less than the angle of incidence

The three loops of wire shown in the figure are all hanging in the same uniform magnetic field that is perpendicular to the page and does not vary with time. Loop 1 swings bak and forth like the bob in a pendulum, Loop 2 rotates about a vertical axis, and Loop 3 oscillates up and down at the end of a spring. Which loop (or loops) will have an emf induced in them

loop 2

One of Einstein's postulates in formulating the special theory or relativity was that the laws of physics are the same in reference frames that

move at a constant velocity with respect to an inertial frame

Light goes from material having a refractive index of n1 into a material with refractive index of n2. If the refracted light is bent away from the normal, what can you conclude about the indices of refraction?

n1 > n2

A light beam has speed c in a vacuum and speed v in a certain plastic. The index of refraction n of this plastic is

n= c/v

You are a passenger on a spaceship. As the speed of the spaceship increases, you will observe

no change in length of your spaceship

Two light sources are said to be coherent if they are

of the same frequency, and maintain a constant phase difference

The figure shows electric field lines arising from two small charged particles P and Q. Consider the following two statements (i) the charge on P is smaller than the charge on Q (ii) the electrostatic force on P is smaller than the force on Q Which of the above statements are true?

only (i) is true

When a current flows through a metal wire, the moving charges are

only electrons

An electron is moving to the right, as shown in the figure. Suddenly it encounters uniform magnetic field pointing out of the page. Which one of the three paths shown will it follow in the field?

path a

A flat coil is in a uniform magnetic field. The magnetic flux through the coil is greatest when the plane of its area is

perpendicular to the magnetic field

An upright object is 50 cm from a concave mirror of radius 60 cm. The character of the image is

real and inverted

In a double-slit interference experiment you are asked to use laser light of different wavelengths and determine the separation between adjacent maxima. You observe that this separation is greatest when you illuminate the double slits with

red light

Which one of the following is not an electromagnetic wave?

sound wave

A hydrogen nucleus, which has a charge of +e, is situated to the left of a carbon nucleus, which has a charge +6e. Which statement is true?

the electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is equal to the force exerted on the carbon nucleus

If a proton and an electron have the same de Broglie wavelength, which one is moving faster?

the electron

A coil lies flat on a tabletop in a region where the magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades

the induced current flows counter clockwise

the critical angle for a beam of light passing from water into air is 48.8 degrees. This means that all light rays with an angle of incidence in the water is greater than 48.8 degrees will be

totally reflected

An electron is initially moving to the right when it enters a uniform electric field directed upwards, as shown in the figure. Which trajectory (X, Y, Z, or W) will the electron follow in the field?

trajectory Z

Light of a given wavelength is used to illuminate the surface of a metal, however, no photoelectrons are emitted. In order to cause electrons to be ejected from the surface of this metal you should

use a light of a shorter wavelength

Which one of the following sets of characteristics describes the image formed by a plane mirror?

virtual and upright