PHYSICS 7 MIDTERM 2 Spring 2010 Question 1:

Size: px

Start display at page:

Download "PHYSICS 7 MIDTERM 2 Spring 2010 Question 1:"

Rosalyn Wheeler
5 years ago
Views:

1 PHYC 7 MDTERM 2 pring 2010 Question 1: (8 pts) how the direction of the loop s induced current in each of the following situations, at the moment shown. Loop expanding in size B into page Magnet moing toward the right Loop at rest Current carrying wire Loop, moing downward

2 MC PHYC 7 MDTERM 2 PRG 2010 page 2 Question 2: (16 pts) An electron is accelerated by being released at rest right next to the negatie plate of a capacitor. t continues to speed up until it reaches the positie plate where it passes through a small hole in to a region of no electric field but constant magnetic field B = T. The electron moes as shown. (a) Draw the electric field and magnetic field on the picture below. electron electron path Region of magnetic field -Q +Q (b) The potential between the plates is 50,000 V and the distance between them is 25.0 cm. What radius circle does the electron make? (c) The electron is replaced by a proton (and the charge on the capacitor plates is reersed from aboe, but eerything else stays the same). What radius circle does the proton moe in when in the region of magnetic field?

3 MC PHYC 7 MDTERM 2 PRG 2010 page 3 Question 3: (12 pts) For each of the situations below, draw the magnetic field at the location marked by a circle (there is a total of X circles). (Use an x if the field is into the page, a dot if it is out of the page, and arrows if it is parallel to the page.) +q Electron moing directly out of the page -e 3

4 MC PHYC 7 MDTERM 2 PRG 2010 page 4 Question 4: (6 pts) how or state the direction of the magnetic force that is felt by the following charges or currents. into page x +q Force on +q =? B Force on wire =? -q Force on -q =? Question 5: (6 pts) A hand-held electric generator works by haing you turn a handle. Turning the handle rotates a coil in a fixed magnetic field. The coil has 375 loops, each of radius 3.0 cm. When you spin the handle at your fastest rate (5 turns per second) you generate an induced oltage of 3.0 olts (the same as two D-cell batteries). What is the strength of the magnetic field (assuming it is constant oer the whole coil)? rotating coil fixed magnet

5 MC PHYC 7 MDTERM 2 PRG 2010 page 5 Question 6: (10 pts) A force of is applied to a m long metal bar which is dragged along two conducting rails at uniform speed. A light bulb of resistance 15.0 connects the other end of the conducting rails, as shown, and glows continuously as the bar is moed through the constant magnetic field B = T. (a) ndicate which way the current flows, and state your reason for choosing it. bulb 0.5 m metal bar B out applied force (b) How much current flows through the bulb? (c) With what constant speed does the bar moe?

6 MC PHYC 7 MDTERM 2 PRG 2010 page 6 Question 7: (6 pts) Fie circular loops are shown edge on in a magnetic field that is uniform and points left. Rank the loop in order from MOT flux to LEAT flux passing through Loop 1 Loop 2 (twice radius of Loop 1) Loop 3 (twice radius of Loop 1) Loop 4 Loop 5 Most Flux Least Flux Loop Loop Loop Loop Loop Question 8: (4 pts) Which way will the current carrying loop (seen edge-on) rotate if released at rest at the position shown? Explain your reasoning x out loop in

7 MC PHYC 7 MDTERM 2 PRG 2010 page 7 Question 9. (10 pts) A helium nucleus (m = 4*m proton ) passes between the two plates of a capacitor, and moes along a straight line while between the plates at a speed of 4.0 x 10 7 m/s. The plates are in a uniform magnetic field (B = T). Which way does E point? Which way does B point? how your reasoning. Magnetic field is non-zero within the boxed region - Q +Q How much charge is on the plates if their area is 0.15 m 2 and separation is 2.5 mm? Question 10:

8 FORMULAE: MC PHYC 7 MDTERM 2 PRG 2010 page 8 B = ( o /4 ) qsin r 2 B wire = o /2 r B loop = o /2r = BA sin F = LB F = qbsin F = ma = - / t = R P = V = 2 R = V 2 /R V 2 /V 1 = 2 / 1 = L i/ t F e = kq 1 q 2 /r 2 E pt = kq/r 2 F electric = qe V = E d for constant E E cap = (Q/A)/ o E E/K in insulator K = ½ m 2 U = q V F = ma F = m 2 /r COTAT: m electron = 9.11 x kg C = 2 R A = R 2 c = 3.00 x 10 8 m/s e = 1.60 x C m proton = 1.67 x kg g = 9.80 m/s 2 1 ev = 1.60 x J k = 9.0 x 10 9 m 2 /C 2 o = 8.85 x C 2 /( m 2 )

a) (4 pts) What is the magnitude and direction of the acceleration of the electron?

a) (4 pts) What is the magnitude and direction of the acceleration of the electron? PHYSCS 22 Fall 2010 - MDTERM #3 SHOW ALL WORK & REASONNG FOR FULL PONTS Question 1. (5 pts): Accurately show or state the direction of the force that is felt by the following charges or currents. +q -q