PHY 112 Finals

At a distance d from a point charge Q, the energy density in its electric field is u. If we now go to a distance d/2 from the charge, what is the energy density at the new location? A) 16u B) 8u C) 4u D) 2u E) u square root of 2

D) 2u

When a dielectric material is introduced between the plates of a parallel-plate capacitor and completely fills the space, the capacitance increases by a factor of 4. What is the dielectric constant of the material that was introduced? A) 0.4 B) 1/4 C) 2 D) 4 E) none of the other choices is correct

D) 4

An ideal parallel-plate capacitor has a capacitance of C. If the area of the plates is doubled and the distance between the plate is halved, what is the new capacitance? A) C/4 B) C.2 C) 2C D) 4C

D) 4C

Two thin slits are 6.00 um apart. Monochromatic coherent light falls on theses slits, and produces a fifth-order bright interference fringe at an angle of 32.3 degrees away from the centerline. What is the wavelength of the light? A) 163 nm B) 416 nm C) 614 nm D) 641 nm

D) 641 nm

X and Y are two initially uncharged metal spheres on insulating stands, and they are in contact with each other. A positively charged rod R is brought close to X as shown in part (a) of the figure. Sphere Y is now moved away from X, as shown in part (b). What are the final charge states of X and Y? A) Both X and Y are neutral B) X is positive and Y is neutral C) X is neutral an Y is positive D) X is negative and Y is Positive E) Both X and Y are negative

D) X is negative and Y is Positive

Two stationary point charges q1 and q2 are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch? A) q1 is negative and q2 is positive; the magnitudes are equal B) q1 and q2 have the same sign; the magnitudes are equal C) q1 is positive and q2 is negative; the magnitude of q1 is greater than the magnitude of q2 D) q1 is negative and q2 is positive, the magnitude of q1 is less than the magnitude of q2 E) q1 and q2 have the same sign; the magnitude of q1 is greater than the magnitude of q2

D) q1 is negative and q2 is positive, the magnitude of q1 is less than the magnitude of q2

A charge of 12C passes through an electroplating apparatus in 2.0 min. What is the average current in the apparatus? A) 0.10 A B) 0.60 A C) 1.0 A D) 6.0 A

A) 0.10 A

An electronic component with a 17- omes resistor is rated for use at power levels not exceeding 14 W. How much current can safely flow through the component? A) 0.91 A B) 1.21 A C) 238 A D) 0.22 A

A) 0.91 A

In a two-slit experiment, monochromatic coherent light of wavelength 600 nm passes through a pair of slits separated by 2.20 *10^-5 m. At what angle away from the centerline does the first bright fringe occur? A) 1.56 degrees B) 2.2 degrees C) 3.12 degrees D) 4.70 degrees E) 6.24 degrees

A) 1.56 degrees

The heating element of a toaster is a 5.4-m length of nichrome wire of diameter 0.48 mm. The resistivity of nichrome at the operating temperature of the toaster is 1.3 * 10^-6 omes*meters. The toaster is designed to operate at a voltage of 120 V. How much power does it draw in normal operation A) 370 W B) 360 W C) 380 W D) 400 W E) 410 W

A) 370 W

Two electrons are 20.0 mm apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other. A) 5.8 * 10^-25 B) 2.3 * 10^10 C) 2.3 N D) 5.8 *10^-27

A) 5.8 * 10^-25

A beam of monochromatic light passes through a slit that is 11.0 um wide. If the first order dark fringe of the resulting diffraction pattern is at an angle of 4.31 degrees away from the centerline, what is the wavelength of light? A) 827 nm B) 301 nm C) 602 nm D) 402 nm E) 201 nm

A) 827 nm

Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of squares of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the center charge. A) A B) B C) C D) D

A) A

Two beams of coherent light start out at the same point in phase and travel different paths to arrive at point P. If the maximum destructive interference is to occur at point P, the two beams must travel paths that differ by A) a whole number of wavelength B) an odd number of half-wavelengths C) a whole number of half- wavelengths

A) a whole number of wavelength

A hydrogen atom consists of a proton and an electron. If the orbital radius of the electron increases, the electric potential energy of the electron due to the proton. A) increases B) decreases C) remains the same D) depends on the zero point of the potential

A) increases

Light having a frequency in vacuum of 6.0*10^14 Hz enters a liquid of refractive index 2.0. What is the frequency of the light in this liquid? (c=3.0 *10^8 m/s) A) 12 *10^14 Hz B) 6.0 *10^14 Hz C) 3.0 *10^14 Hz D) 1.5 *10^14 Hz E) 2.0 *10^14 Hz

B) 6.0 *10^14 Hz

The plates of a parallel-plate capacitor are maintained with constant voltage by a battery as they are pulled apart. What happens to the strength of the electric field between the plates during this process? A) it increases B) it decreases C) it remains constant D) it cannot be determined from the information given

B) it decreases

Monochromatic coherent light shines through a pair of slits. if the distance between theses slits is decreased, which of the following statements are true of the resulting interference pattern? (There could be more than one correct choice) A) The distance between the maxima stays the same B) the distance between the maxima decreases C) the distance between the minima stays the same D) the distance between the minima increases E) the distance between the maxima increases

B) the distance between the maxima decreases

The distance between two slits is 1.50*10^-5 m. A beam of coherent light of wavelength 600 nm illuminates these slits, and the distance between the slit and the screen is 2.00 m. What is the distance on the screen between the central bright fringe and the fourth0order bright fringe? A) 0.132 m B) 0.201 m C) 0.324 m D) 0.528 m E) 0.688 m

C) 0.324 m

Light of wavelength 610 nm is incident on a list 0.20 nm wide and the diffraction pattern is viewed on a screen that is 1.5 m from the slit. What is the width on the screen of the central maximum? A) 0.34 cm B) 0.68 cm C) 0.92 cm D) 1.2 cm

C) 0.92 cm

Light having a speed in vacuum of 3.0*10^8 m/s enters a liquid of refractive index 2.0. In this liquid, its speed will be A) 6.0 *10^8 m/s B) 3.0 *10^8 m/s C) 1.5 *10^8 m/s D) 0.75 *10^8 m/s E) 0.67 *10^8 m/s

C) 1.5 *10^8 m/s

In a two-slit experiment, monochromatic coherent light of wavelength 600 nm passes through a pair of slits separated by 2.20 *10^-5 m. At what angle away from the centerline does the second dark fringe occur? A) 4.0 degrees B) 3.51 degrees C) 3.94 degrees D) 1.17 degrees E) 2.34 degrees

C) 3.94 degrees

What principle is responsible for light spreading as it passes through a narrow slit? A) Refraction B) Polarization C) diffraction D) dispersion

C) diffraction

When a beam of light , originally traveling in air, enters a piece of glass having an index of refraction of 3/2, its frequency A) increases by a factor of 3/2 B) is reduced to 2/3 its original value C) is unaffected

C) is unaffected

In a single-slit diffraction experiment, the width of the slit through which passes is reduced. What happens to the width of the central bright fringe in the resulting diffraction pattern? A) it stays the same B) it becomes narrower C) it becomes wider

C) it becomes wider