ex3.f07

# ex3.f07 - PHY204 UNIT EXAM 3 Nov 23 2007 Name Problem 1 An...

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Unformatted text preview: PHY204 UNIT EXAM 3 Nov. 23, 2007 - Name Problem 1 An electron (mass m = 9.] 1x10‘31 kg, charge q = -l.6x10'19 C) has a speed V = 2.0x107 m/s when it enters (at point A) a region of magnetic ﬁeld B directed perpendicular to the plane of the sheet. The ﬁeld provides a centripetal force of magnitude F: 5.0x 10'15 N that bends the path of the electron into a semicircle of radius r, as shown. (a) Find the magnitude 3 of the magnetic ﬁeld. (b) Find the radius r of the circle. (0) liind the speed VI of the electron as it exits the region ofmagnetic ﬁeld at point (7. (d) Find the direction (out ofthe plane; or into the plane) ot‘the field B. %ya, F: ii (a) B t: 1,5; ruf’ﬂ 2x107 I?” :2! “diff/ﬂ‘wL‘E/ ll CT“. [9 : _, g “i ( ) r F 5" lOJ/T rﬁi/ V— ‘- ﬁ—é— , 1/ m w (ill vzromd, _ V! :szsgo T,- (d/ f; (gm/2 ; 5 <9 mag/aw l (-)“r‘ 69 " I“) Problem 2 A very long, straight wire at x = 1m carries current 11 = 6A, and a second long wire at x = 3m carries current 13 = 3A. The current directions are as shown. Find magnitude and direction {up/down/right/left/into plane/out of plane) of the magnetic ﬁeld (a) 30 at x = 0; I l= 6A I3= 3A (1)) B; atx = 2m; (c) Bi atx = 4m. (7 (kaoufé {1/9” W 94"!”{CA‘2L1 afﬂ/DOII‘B‘L/Q» 8' B :4": _£ 3:; r - __é 3 0 92,7 ,ZK/U // + 3 [30 wamw‘g'x‘r—AO/T/ 5’0 (o 8 251* I4 1 " . - , K j 2, ’27 +(lm)) 2m; /(+§/,/,8Ar/0 r52 7+/,3://¢A T/'_‘ [32 7 2] {41/ Beg" £1-33 : ’ “32-0.: Problem 3 A conducting square frame with sides of length L = 2m and electn'cal resistance R = 100 is placed in the yz-plane as shown. A unifonn magnetic ﬁeld B = Bxi is applied perpendicular to the yz-plane. The dependence of B,i on time t is shown graphically. Find magnitude and direction (cw/cow) of the induced current I (a) at timer: Is; 2 BAT] (b) at t1mer=3s. 3 3 21 4 2m 0 A (broom A =/lg (600 Y -1 1 2 3 2 A=4>rw X Fiﬁ/(acea/ C6"? "TE-L 7/ ﬁr, LE- ~Z’ (a) M t S (7H , LS 0,5 5 £1 ~4M5’: ~30 V; CW "’ g— —-—’g'--:"' A 11:72] ’ l0 / Midi ; {I (lo/Au #225 27,02? A 3 5M t[s] ...
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