Physics Final

Which one of the following statements concerning rays is false?

Rays are parallel to the wave front

Which one of the following statements is not a characteristic of a plane mirror?

The image is real

A long, straight wire, oriented left to right is in the same vertical plane as a rectangular, conducting loop. The wire carries a constant current I towards the right. The loop lies below the wire. Which one of the following statements is true if the wire is suddenly moved toward the loop?

There will be an induced current that is counterclockwise around the loop.

The owner of a van installs a rear-window lens that has a focal length of -0.300 m. When the owner looks out through the lens at a person standing directly behind the van, the person appears to be just 0.240 m from the back of the van, and appears to be 0.34 m tall. (a) How far from the van is the person actually standing, and (b) how tall is the person? Note: The image of the person is upright and virtual.

a) 1.2 m (b) 1.7 m

A mirror produces an image that is located 34.0 cm behind the mirror when the object is located 7.50 cm in front of the mirror. What is the focal length of the mirror, and is the mirror concave or convex?

a) 9.6 cm (b) concave

two loops that are carrying current in the same direction will

attract each other

the electric potential __________________ as you go out from a positive charge.

decreases

A 4-cm object is placed in front of a converging lens of focal length 20 cm. The image is formed 60 cm on the other side of the lens. What are the object distance and the magnitude of the image height?

do = 30 cm; |hi| = 8 cm

you have a horizontal wire with a north-south orientation. It is carrying current in the northward direction. In what direction is the magnetic field at a point 0.5 m east of the wire (at the same height as the wire)?

downward

A convex mirror always forms an image that is

reduced in size, upright, and virtual.

What is the correct order, beginning with shortest wavelength and extending to the longest wavelength, of the following colors in the visible light spectrum: blue, green, red, violet, and yellow?

violet, blue, green, yellow, red

A long, straight wire carries a 6.0-A current that is directed in the positive x direction. When a uniform magnetic field is applied perpendicular to a 3.0-m segment of the wire, the magnetic force on the segment is 0.36 N, directed in the negative y direction. What are the magnitude and direction of the magnetic field? Note: the x- and y- axes lie in the plane of the paper.

0.020 T, out of the paper

charge Q exerts a 1.2 N force on another charge q. If the distance between the charges is doubled, what is the magnitude of the force exerted on q by Q?

0.30 N

The Earth's magnetic field passes through a square, horizontal tabletop with a magnitude of 4.95 × 10-5T and is directed downward at an angle of 15° relative to the vertical. If the tabletop has 1.50-m sides, what is the magnitude of the magnetic flux through it?

1.08 × 10-4 Wb

Suppose that the electric potential outside a living cell is higher than that inside the cell by 0.070 V. How much work is done by the electric force when a sodium ion (charge = +e) moves from the outside to the inside? (Be careful of the positive and negative signs.)

1.12 x 10^-20 J

When a radio telescope observes a region of space between two stars, it detects electromagnetic radiation that has a wavelength of 0.21 m. This radiation was emitted by hydrogen atoms in the gas and dust located in that region. What is the frequency of this radiation?

1.4 × 109 Hz

A fish swims 2.00 m below the surface of a pond. At what apparent depth does the fish appear to swim if viewed from directly above? The index of refraction of water is 1.33.

1.50 m

A single circular loop of wire of radius 0.45 m carries a constant current of 2.4 A. The loop may be rotated about an axis that passes through the center and lies in the plane of the loop. When the orientation of the normal to the loop with respect to the direction of the magnetic field is 36°, the torque on the coil is 1.5 N x m. What is the magnitude of the magnetic field exerting this torque on the loop?

1.7 T

A parallel plate capacitor has plates of area 2.0 ×10-3 m 2 and plate separation of 1.0 ×10-4m. Determine the capacitance of this system if air fills the volume between the plates.

1.8 ×10^-10 F

A potential difference of 120 V is established between two parallel metal plates. The magnitude of the charge on each plate is 0.020 C. What is the capacitance of this capacitor?

170 μF

Two coils are placed next to each other. Their long axes lie in the same direction. The mutual inductance of this pair of coils is 6.0 mH. If the current in coil 1 is changing at the rate of 3.5 A/s, what is the magnitude of the emf generated in coil 2?

2.1 × 10-2 V

three resistors, 4.0-Ω, 8.0-Ω, 16-Ω, are connected in parallel in a circuit. What is the equivalent resistance of this combination of resistors?

2.3 Ω

A light ray is traveling in a diamond (n = 2.419). If the ray approaches the diamond-air interface, what is the minimum angle of incidence (i.e., what is the critical angle) that will result in all of the light reflected back into the diamond? The index of refraction for air is 1.000.

24.42°

three parallel plate capacitors, each having a capacitance of 1.0 μF, are connected in parallel. The potential difference across the combination is 100 V. What is the equivalent capacitance of this combination?

3 μF

when a light bulb is connected to a 4.5 V battery, a current of 0.12 A passes through the bulb filament. What is the resistance of the filament?

38 Ω

The battery charger for an MP3 player contains a step-down transformer with a turns ratio of 1:30, so that the voltage of 120 V available at a wall socket can be used to charge the battery pack or operate the player. What voltage does the secondary coil of the transformer provide? (Note: turns ratio = NS/NP)

4.0 V

find the equivalent resistance between points A and B in the drawing.

4.67 ohms

A wire is stretched horizontally between two vertical posts. The wire carries a current of 100 A and experiences a magnetic force of 0.20 N. The earth's magnetic field has a value of 5.13 x 10-5 T at the location of the wire and makes an angle of 60.0° with respect to the wire. How long is the wire?

45 m

What would the speed of an observer be if a red (4.688 × 1014Hz) traffic light appeared green (5.555 × 1014Hz) to the observer?

5.548 × 107 m/s

A flexible, circular conducting loop of radius 0.15 m and resistance 4.0 Ω lies in a uniform magnetic field of 0.25 T. The magnetic field is perpendicular to the plane of the loop. The loop is pulled on opposite sides by equal forces and stretched until its enclosed area is essentially zero m2. It takes 0.30 s to close the loop. Determine the magnitude of the emf induced in the loop.

5.9 × 10 -2 V

A scuba diver shines a flashlight from beneath the surface of water (n = 1.33) such that the light strikes the water-air boundary with an angle of incidence of 37°. At what angle is the beam refracted?

53°

The magnetic field inside a solenoid with 500 turns per meter and a current of 1 A is

6.28 x 10-4 T

determine the energy stored in a 7.09 × 10-7 H inductor that carries a 1.50-A current.

7.98 × 10-7 J

determine the length of a copper wire that has a resistance of 0.172 Ω and cross-sectional area of 7.85 ×10-5 m2. The resistivity of copper is 1.72 ×10-8Ωxm.

785 m

What is the magnitude of the electric field due to a 6.0 ×10-9 C charge at a point located 0.025 m from the charge?

8.6 × 10^4 N/C

A transformer changes 120 V across the primary to 1200 V across the secondary. If the secondary coil has 800 turns, how many turns does the primary coil have?

80

what is the correct order of steps when charging by induction?

Bring the charged rod close to (but not touching) the sphere, connect the sphere to ground, disconnect the sphere from ground, remove the rod.

Unpolarized light of intensity I passes through two sheets of polarizing material whose transmission axes make an angle of 60° with each other. What is the intensity of the transmitted beam, S?

I/8

Can the magnetic force on a charge moving through a magnetic field do work on the charge?

No

convex mirror with a focal length of 58 cm is used to form an image that is 29 cm behind the mirror. What is the object distance?

+58 cm

you have a charge of -3.0 μC. Wh at is the electric potential (a.k.a. the voltage) at a distance of 2 m from the charge?

-1.3 x 10^4 V

For the same distance between the charges, which combination of charges would yield the greatest repulsive force between the charges? Assume that q has the same value for all the charges.

-2q and -4q