Physics 2 Lecture Final Exam

CERN estimates that it would take about 2.5 × 10^16 kWh of energy to produce a gram of antimatter. At a going rate of $0.11 per kWh, what would be the cost of making a gram of antimatter?

$2,750,000,000,000,000

A gold wire has a hollow core. The outside diameter is 5.00cm and the inside diameter is 3.00cm. What is the resistance of a 10.0m length of this pipe? ρ = 2.44 × 10^−8 Ω⋅m

0.000194 ohms

A bird stands on a dc electric transmission line carrying 4100 A. The line has a 2.5 × 10^−5 Ω resistance per meter of line, and the bird's feet are 4.0 cm apart. What is the potential difference between the bird's feet? Your answer will have units of Volts. Type in the number without the units.

0.0041

A circular coil of 20 turns and radius 5.0 cm is placed with its plane oriented at 90 degrees to a uniform magnetic field of 0.10 Tesla. The field is now increased at a steady rate, reaching a value of 0.5 Tesla after 4.0 seconds. What emf is induced in the coil?

0.016 V

!!! The focal length of the lens of a simple film camera is 40.0 mm. By what amount should the distance between the lens and the film be increased or decreased to change the focus from a person who is 25 m from the lens to one who is 4.0 m from the lens?

0.3 mm

Find the current coming out of the battery in the following circuit. (image) (9 V, 90 Ω, 45 Ω, 180 Ω)

0.35 Amps

How fast must a meter stick move, relative to the frame of the observer making the measurement, so its length will be measured to be 0.60 m?

0.80c

Three particles travel through a region of space where the magnetic field is out of the page, as shown in the figure. What are the signs of the charges of these three particles? (image)

1 is negative, 2 is neutral, and 3 is positive.

A certain part of the electromagnetic spectrum ranges from 200 nm to 400 nm. What is the highest frequency associated with this portion of the spectrum? (c = 3.00 × 108 m/s)

1.50 × 10^15 Hz

An electron moves with a speed of 3.0 × 10^4 m/s perpendicular to a uniform magnetic field of 0.40T. What is the magnitude of the magnetic force on the electron? e = 1.60 × 10^−19 C

1.9x10^-15 N

!!! Which one of the following expressions is the correct representation for the speed of light in vacuum?

1/sq rt (ε0μ0)

!!! A glass plate with an index of refraction is 1.57 is immersed in an oil having a refractive index of 1.40. The surface of the glass is inclined at an angle of 54 degrees with the vertical. A horizontal light ray in the glass strikes the interface. What is the angle that the refracted ray, in the oil, makes with the horizontal?

11 degrees

!!! A current of 2.0 A in the 100-turn primary of an ideal transformer causes 14 A to flow in the secondary. How many turns are in the secondary?

14

Convert 170.0 kiloelectronvolts to Joules. 170.0 keV = _________ J

2.7237 x 10^-14

An electron moves with a speed of 8.0 × 10^6 m/s along the +x-axis. It enters a region where there is a magnetic field of 2.5T, directed at an angle of 60 degrees to the +x-axis and lying in the xy-plane. Calculate the magnitude of the magnetic force on the electron. e = 1.60 × 10^−19 C

2.8 x 10^-12 N

The following three appliances are connected in parallel across an ideal 120-V dc power source: 1200-W toaster, 650-W coffee pot, and 600-W microwave. If all were operated at the same time what total current would they draw from the source?

20 A

!!! 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

When 5.0 A at 110 V flows in the primary of an ideal transformer, how many amps at 24 V can flow in the secondary?

23 A

!!! When 5.00 A is flowing through an 10.0 ohm device, how much power is being dissipated in the device?

250 W

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 the observer on Earth?

3.6 s

A light ray in glass arrives at the glass-water interface at an angle of θ = 48° with the normal. The refracted ray in water makes an angle θ = 61° with the normal, as shown in the figure. The index of refraction of water is 1.33. The angle of incidence is now changed to θ = 25°. What is the new angle of refraction φ in the water? (image)

30°

Calculate the magnitude of the electric field at one corner of a square with sides 1.22m in length if the other three corners are occupied by 3.25 × 10^−6 C charges. Your answer will have units of Newtons per Coulomb. Type in the number without the units.

37,618.1

!!! If a charge generator builds a negative static charge of -7.00 microC, how many electrons are transferred to it during this process. (e = 1.60 x 10^19 C)

4.38*10^13

In an ideal transformer, how many turns are necessary in a 110-V primary if the 24-V secondary has 100 turns?

458

An electron is accelerated from rest through a potential difference of 3.75 kV. It enters a region where a uniform 4.0-mT magnetic field is perpendicular to the velocity of the electron. Calculate the radius of the path this electron will follow in the magnetic field. e = 1.60 × 10^−19 C, melectron = 9.11 × 10^−31 kg

5.2 cm

If an electron is accelerated from rest through a potential difference of 9.9 kV, what is its resulting speed? For reference: e = 1.60 × 10^−19 C, k = 1/(4πϵ0) = 8.99 × 10^9 N⋅m2/C2, me = 9.11 × 10^−31 kg

5.897 x 10^7 m/s

!!! The wavelength of an electromagnetic wave is 600 nm. What is its frequency? (c = 3.0 x 10^8 m/s)

500 x 10^12 Hz

!!! A ray of light (ray a) in air strikes a flat piece of glass at an angle of φ0 = 84 degrees with respect to the normal, as shown in the figure. The index of refraction of the glass is 1.5. What is the angle theta between the reflected ray (ray b) and refracted ray (ray c) rays? (image) Your answer will have units of degrees. Simply type the number without the units.

55

A 4.0-Ω resistor is connected to a 12-Ω resistor and this combination is connected to an ideal dc power supply with voltage V as shown in the figure. If the total current in this circuit is I = 2.0 A, what is the value of voltage V? Your answer will have units of Volts. Type in the number without the units. (image)

6

!!! How far does a beam of light travel in 2.0 ms? (c = 3.0 x 10^8 m/s)

6.0 x 10^5 m

!!! A radio station broadcasts at 80 MHz. How long does it take for this radio signal to travel a distance of 2.0 x 10^7 m through space? (c = 3.0 x 10^8 m/s)

6.7 x 10^-2 s

As shown in the figure, a laser positioned on a ship is used to communicate with a small research submarine resting on the bottom of a lake. The laser is positioned 12 m above the surface of the water, and it strikes the water 20 m from the side of the ship. The water is 58 m deep and has an index of refraction of 1.33. How far horizontally is the submarine from the side of the ship? (Assume all numbers are accurate to three significant figures.) (image)

69 m

Two stars are at rest relative to each other. A spaceship is moving between these two stars at 0.932c relative to each star. To someone in the ship, the distance between the two stars appears to be 26.4 light-years. What is the distance between the stars in their own rest frame?

72.8 light-years

The following circuit has 3 resistors. R1=2Ω, R2=4Ω, R3=8Ω.What is the total equivalent resistance of the circuit? (image)

8/7 Ω

What potential difference is needed to give a helium nucleus (Q=2e) 170.0 keV of kinetic energy? Your answer will have units of Volts. Type in the number without the units.

85,000

How far does a beam of light travel through space in one 365-day year? (c = 3.0 × 10^8 m/s)

95 × 10^14 m

!!! Four point charges Q of equal magnitude and sign are arranged on three of the corners of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square? (image)

D

!!! The three loops of wire shown in the figure are all hanging in the same uniform magnetic field (vector B) that is perpendicular to the page and does not vary with time. Loop 1 swings back 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? (Image)

Loop 2

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. 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 counterclockwise.

!!! A proton, moving north, enters a magnetic field. Because of this field, the proton curves downward. We may conclude that the magnetic field must have a component

Towards the east

!!! 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? (Image)

Trajectory Z

A lighted candle is placed a short distance from a plane mirror, as shown in the figure. At which location will the image of the flame appear to be located? (image)

at C

The focal length of the lens of a simple digital camera is 40 mm, and it is originally focused on a person 25 m away. In what direction must the lens be moved to change the focus of the camera to a person 4.0 m away?

away from the CCD sensors

The figure show four Gaussian surfaces surrounding a distribution of charges. (image) Which Gaussian surface has an electric flux of +q/ϵ0 through it?

b

!!! If the voltage across a circuit of constant resistance is doubled, the power dissipated by that circuit will

be four times as large

Which of the following attempts will light up the bulb? (image)

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.

An outer metal ring surrounds an inner metal ring, as shown in the figure. The current in the outer ring is counterclockwise and decreasing. What is the direction of the induced current in the inner ring? (image)

counterclockwise

If the back of a person's eye is too close to the lens, this person is suffering from

farsightedness.

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

greater than the angle of incidence.

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

n = c/v

If the lens in a person's eye is too highly cured, this person is suffering from

nearsightedness.

Two light sources are said to be coherent if they are

of the same frequency, and maintain a constant phase difference.

Which one of the following lists gives the correct order of the electromagnetic spectrum from low to high frequencies?

radio waves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays

!!! Which one of the following is not an electromagnetic wave?

sound waves

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

virtual and upright