physics

Spring,2014 PHYS 183 Practice Test I (5llll4) Name You will be asked to make calculations, explain things and draw diagrams on this test. Please show all ofyour work. IfI don't see your work, I can't give you partial credit and won't give you full credit. Also, include proper units with your answer for full credit. You may use the formulas provided This test is worth 64 points Good luck. Ifyou studied for this test, you have the potential to do well.

l. a.) Sk€tch the electric field lines cieated by the three point charges. (Show direction and relativ€ number of field lines for the region near each charge.) [5 points]

b.) Put an "X" at the location(s) near the charges where the elecrric field due to the charges is zero [1 pt]

2. Three point charges are located at the comers ofa 45'-45'_90" triangle as shown below. Calculat€ the net electria force on q2. ql = -4.0 pC, q, = 4.0 !rC, qr = 4 O pC. Your answer may be in unit vector notation qI by expressing a magnitude and direction with th€ angle clearly labeled [10 points]

q3

1.0 m

q2

Print the letter conesponding to the b9{ answer in front ofthe following items. Each item is worth 2 points. You may get partial creditby putting 2 letters in the space. Ifyou put I l€tter in the space and it's correct you get 2 points. lfyou put 2 letters in the box and I is co.rect, you get I point. Ifnone ofyour letters in the space are conect or ifyou put more than 2 letters in the space or I can't read your letters, you get 0 points.

Spring,2014 PHYS 183 Practice Test 1 (5lll14) Name

Two particles have charges Q and -Q (equal magnitude and opposite siSn). For a net force ofzero to be exerted on a third charge it must be placed a, midway between Q and -Q, b. on the perpendicular bisector ofthe line joining Q and -Q, br.rt not on that line itself. c. on the linejoining Q and -Q, to the side ofQ opposite -Q. d. on the line joining Q and -Q, to the side of-Q opposite Q e. at none ofthese positions (there is no position that works).

An isolated point charge produces an electric field with magnitude E at a point 2 m away A point at which the field magnilude is E/4 is a. 1 m away from the point charge. b. 0.5 m away from the point charge. c. 2 m away from the point charge. d. 4 m away from the point charge. e. 8 m away from the point charge.

When a positive charge moves in the direction ofan elechic field (i.e,, in the dircction ofthe electric field lines),

5.

6.

a. b. c. d.

The electaic field does positive work on the charge. The charye loses electdc potential energy. The charge gains electric potential energy. a and b are true.

'7.

8.

When a piece oipaper is held with one face perpendicular to a uniform electric field the flux through is

25 Nm2/C. When the paper is tumed 25o with respect to the field, the flux through it is a. o Nm2/c. b. t2 Nm'?/c. c. 21 Nm'z/c. d. 23 Nrn'/c. e. 25 Nm2/c.

A +15 C charge is placed on a spherical conducting shell. A -5 C point charge is placed at the center of the empty cavity. The net charge in coulombs on the outer surface ofthe shell is a. +10 C. b. +5c. c.0C. d -5 c. e. -10 C.

The eleckic field strenglh 5.0 cm from the middle ofa l 0 mile long thin wire is 1000 N/C. what is the electric field strenglh 10.0 cm from the wirc? a. 250 N/C. b. 500 N/c. c. 1000 N/C d.2000N/c. e. 4000 N/C.

Spring,2014 PI{YS 183 Practice Test 1 (5llll4) Name icle thar has the safte charge as a proton but rhe same mass as9. A positron is a

b. .How much€lectric potential.energy does it gai4or lose? [3 points] c, ' How muih kinetic energy, tloes it gain or lose? [2 points] .

10. Charge A, L0 x 10-6 C, is located at the origin. Chargq B, -1.0 x 10-6 C, is located on the positive x axis at x = 3.0 meter. Determine the magnitude and direction ofthe electric field at a point 2.0 meier to the righl of charge B. Your answer may be in unit vector notation ql by expressing a magnitude and direction with the angle clearly labeled. [8 pointsl

an electron..-Suppose a field-"suclias that of a

Spring,2014 PHYS 183 Practice Test 1 (5/l/14) Name- I i . An-insulating solid sphere with a radius of I .0 m has a L0 X I 0

6 C charge distributed uniformly throughout its

volume, Find the electric field at the following locations. a) 0.30 m f.om the center of the sphere 16 pointsl b) 3.0 m from the center ofthe sphere [4 points]

I 4. A oroton m oves at 6.0 ' I0 t m/s in the +x direction (horizontal). lt enters a uniform electdc field of 6.d ' I0' N/c directed in the y direction. lgnore any gravitalional effects

a. How long does it take the proton to kavel 0 20 m horizontally? [4 points]

b. What is its vertical displacem€nt after it has traveled 0.20 m horizontally? [6 points]