General Physics, Test 2 1) An interference pattern isproduced by light from a mo

Question

General Physics, Test 2

1) An interference pattern isproduced by light from a monochromatic source passing through a double slit. The amplitude of the pattern at the very center is at a maximum becuase the path difference from each slit to the center of the screen:

A) is zero

B) Is maximum

C) Differs by one full wavelength

D) Differs by one half of a wavelength

2) An optical engineer needs to ensure that the bright finges from a double-slit are 15.7 mm apart on a detector that is 1.70 m from the slits. If the slits are illumiated with coherant light of wavelength 633 nm, how far apart should the slits be?

A) 74.0 micrometers

B) 79.5 micrometers

C) 68.5 micrometers

D) 63.0 micrometers

3) The critical angle fro 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 that is greater than 48.8 degrees will be:

A) Totally absorbed by the water

B) Totally reflected

C) Partially reflected and partially transmitted

D) Totally transmitted

4) A beam of light traveling in air strikes a glass slab at an angle of incidence less than 90 degress. After entering the glass slab, what does the beam of light do?

A) It follows the same path as before it struck the glass.

B) It follows the normal to the glass slab.

C) It bends closer to the normal at the point of contact.

D) It bends away from the normal at the point of contact.

5) An object is placed sat the focal point of a thin convex lens. Which of the following statements best describes the image that forms?

A) The image is real, forming at the focal length on the side of the lens opposite the object.

B) The image is virtual, forming at twice the focal length on the same side of the lens as the object.

C) The image is real, forming twice the focal length on the side of the lens opposite the object.

D) No image will form.

6) 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?

A) 20.9

B) 51.8

C) 47.5

D) 14.9

E) 30.0

7) An object is 5.7 cm from a spherical concave mirror. If the image is 4.7 cm tall and 10 cm from the mirror, how tall is the object?

A) 11 cm

B) 8.2 cm

C) 2.7 cm

D) 12 cm

9) A negatively charged rod is brought near a second rod that is neutral and suspended by a non-conducting string. The second rod begins to move toward the negative rod, showing attraction between the two rods. After the first rod is removed, the second rod....?

A) Has no net charge.

B) Has a positive net charge.

C) Has a negative net charge

D) Is polarized with one end negative and the other positive.

10) The electric force between two charged objects is 0.02 N. If the objects are moved four times apart, what is the new force?

A) 0.0013 N

B) 0.0025 N

C) 0.0050 N

D) 0.01 N

12) In a laboratory, an oil droplet carrying a two-electron charge is observed to hover between electrically charged plates so that the electric force upward is equal to the gravitational force downward. Which of the following expressions can be used to determine the mass of the oil droplet?

A) m= gE/ 2e

B) m= 2eE/g

C) m= eE/g

D) m= gE/e

13) How many electrons are transferred in the process of charging a latex balloon to 1.6 x 10^-8 C?

A) 1 x 10^11

B) 2.56 x 10^-27

C) 1 x 10^27

D) 1 x 10^-25

15) A small object with a 5.0 microC charge is accelerating horizontally on a friction-free surface at 0.0050 m/s^2 due only to an electric field. If the object has a mass of 2.0 g, what is the magnitude of the electric field?

A) 2.0 N/C

B) 0.0020 N/C

C) 1.0 N/C

D) 4.0 N/C

E) 0.0040 N/C

16) Eight ions of equal charge, +Q are arranged on the corners of a cube with sides of length d. What is the magnitude of the net electric field at the center of the cube?

A) k Q/d^2

B) k 8Q/d^2

C) k 32Q/3d^2

D) k 8Q/d^2 cos(45)

E) Zero

Explanation / Answer

1) Option A) is correct. Path difference = zero

2) slit spacing = wavelength * distance to screen / distance between fringes

= (633*10^-9*1.7)/(15.7*10^-3) = 68.5 um (option C)

3)  totally reflected.(Option B)

4) C) It bends closer to the normal at the point of contact.(Because glass is more denser than air)

5)

6) Option A) is correct

Angle of refraction = sin-1(sin30/1.4) = 20.9

7)

10) A) 0.0013 N As F = kq1q2/r^2

13) A) 1 x 10^11   As n = Q/e = 1.6*10^-8/1.6*10^-19 = 1*10^11

15) A) 2.0 N/C

F = ma = qE ====> E = ma/q = (2*10^-3*0.0050)/5*10^-6 = 2 N/C

16) E) Zero   Due to symmetry, net field will be zero.

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