physics 1B keating solution quiz 4

# physics 1B keating solution quiz 4 - Quiz 4 Solutions These...

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Unformatted text preview: Quiz 4 Solutions These solutions are written for version A. The questions for versions B and C are related as follows: A B C 1 —> 2 1 2 —> 4 3 3 —> 6 5 4 —> 8 7 5 —> 10 9 6 —> 1 2 7 —> 3 4 8 —> 5 6 9 —> 7 8 10 —> 9 10 1. The electron moves parallel to the magnetic ﬁeld, so 6 = 0, thus F = (1113 sin(6) becomes F = qu sin(0) = 0. 2. As with 1., we have theta = 0 such that F = BIlsin(6) = 0, 3. Using our right hand rule, we can ﬁnd the direction of the magnetic ﬁeld due to wire 1 at wire 2. Then, using our right hand rule for the force, we ﬁnd that the current of wire 2 being opposite in direction to the current of wire 1 gives us a repulsive force. 4- Usng § = % we get (0.8%,) = (4”X10_7T2,132/2§31§‘;"0A)(10A). This gives us F = 3.2x10-5 N, (a)- t N 0 = #00041” = 2x10’3 T, (a). 5' B : 271'1’ 27r(1m) 6. Using (1)3 2 BA cos(6). Here, our area lies perpendicular to the magnetic ﬁeld, thus 6 = 0 between the magnetic ﬁeld and the normal of the area (ie, the line that comes out perpendicular to the area). This gives us <I>B = (4.5 T)(0.10 m2) = .45 T-m2, (b). 7. The current is held constant in the primary wire, thus there is no changing ﬁux. Without a changing flux, there can be no induced current, so the answer is zero, 8. To ﬁnd the induced current, we must ﬁrst ﬁnd the induced EMF. Where 5 = —NAAitB. Using (1)3 2 BA cos(6), we get ABAcos(0) = _N— 6 At 2 IR _ ABAcos(6) 2‘1 — _NA—tR _ 4(25—10mT)(200cm2) (5ms)(5.09) Which gives us I = 48 mA, 9. When the magnet ﬁrst enters the loop, the induced current creates a magnetic ﬁeld to oppose the magnet. Once the center of the magnet passes through the loop, the loop’s current now creates a magnetic ﬁeld to try to attract the magnet. Remember that induced current resists change. Thus the current would be induced to create a magnetic field pointing downwards (or into the page as viewed from above). This would be caused by a clockwise moving current (as viewed from above), (a). 10. A generator is a moving piece of wire that creates a current; thus, mechanical energy is converted into electric energy, (a). ...
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physics 1B keating solution quiz 4 - Quiz 4 Solutions These...

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