PHYS 205 Final, Spring 2008

Useful Information (®) Physical Constants h=6.626x10"J.§ he = 1.242 x 10* eV.m R = 1.097x 10 1/m (Rydberg constant) f=4n x 10’ Wh(Am) * Na =6.02x 10” I/mole — (Avogadro Number) m,= 9.11 x10 kg K=9x10°N.m/C’ (Coulomb constant) (b) Atomic Masses Atomic Mass 1.007825 1.008665 26.981541 26.986721 a @. Koray of wavelength i= ™ 0.180 nm are scattered by clectrona from s bloek of carbon. Themed Kee od ang o 6 expe the incident beam: (a) The kinetic energy of the recoil electrons is (i &V) : Os4 (Jo7 0 80 0 180 0 none of the above, my answor is (b) The maximum energy that a recoil electron can achiove is (in ¢V) 0 44 Oe , Ore 0) 27 O none of the above, my answer is Q. The estimated wavelength of the Kg X-ray emitted from a Nickel target (Z = 28) is (in nm) : 0 0.50 0) 0.035 Oo3s Cos. oO 0.028 O none of the above, my answer is: Q. An electron in the hydrogen atom “jumps” from some initial Bohr orbit (n;) to some final orbit (ng). The photon emitted is capable of ejecting photoelectrons from a tungsten target (see Figure), whose work function is 4.58 eV. ‘ (a) The value of ng is : n= (b) If the stopping potential is v, = 7.51 V, then the value of nj is: n= Q. In the figure below: is fit changed by dong the _ switch S, . Swith eee opened and switch S; is closed, (2) The final charge on capacitor C, is (in uC): E120 Cho - Ceo Q. Two long parallel conductors into the page (see Figure). carry currents I, = = 3 A, Both currents are di i (2) The magnitude of the resultant Lhupward Uo the left L lto the tight Cldownward = 8 F4 x 10 te Bg) i 2: . ye 4 B.4qxd xBlqZ d dart ae ¢ = SRA 3g, a. 1. Five charges are placed in a closed bor. Each charge, has a magnitude which is twice that of the previous one placed in the box. All charges are positive. After placing all the charges in the box, the net clectric flux is $,. 4 - 2 Ly 3. -(@) The magnitude of the smaiiest charge in the box is: Dise/e. Claseetee (p25 & 1p./308. C) none of the above, my answer is (b) If the size of the box is doubled, the magnitude of the gquallot change: (witt be doubled [1 wil remain. the same C1 I cannot determine, without further information —_ Q. In the circuit shown below: 6 = 12V, C = 6.50 pF, R= R, = Ry =8x 10°. The capacitor is initially uncharged, and the switch S * Qs Dea Oo2 Ooso [oss Canons of the above, my anaweris LOT (b) The average power diasipated in the circuit at resonance is (in J) O32 O32 Ooss 1] 0.92 LD none of the above, my answer is CL J (©) What is the phase angle @ between the current and the applied voltage ? Cat We see N, = 2000, and N, = 100 The impedance Z, is then : Answer: Q. The circuit shown in the Figure is placed in a uniform magnetic field which point into the page. The magnetic field is decreasing at arate 150 T/S. (a) The current in the circuit is (in A): 0 0.22 [Tos wo 40 . 0 none of the above, my answer is (a) The initial activity of the sample is (in Bq): O 12310 0 3.4610" 1 1.10 x 10° J 5.86 x10” Q none of the above, my answer is: ; (b) The time needed for this radioactive material to reduce its activity to the level of 0.10 Bq is (in years) 3 C] 346x10 1 iiox10! OC] 5.86 x10" a 1.23x1¢ (J none of the above, my answer is — Q Immediately after the swich Sis closed in the circuit shown, the current is: 0 zero O VSR: O ViR+R) O v, Stk RR, O none of the above, my answer is (b) After a long time, the switch is opened. Immedialtely after the switch is opned, the current in the inductor is Ove Ovwr Over Ov, f. “B) 4 *‘2 OO zero C1 none of the above, my answer is Q. In the circuit shown in the Figure, when the switch S is closed, the resistance: between points a and b drops to one-half Of its initial value (before S is closed). (®) The value of the resistor R is (in (2): Ow Ov O w Lis) 0 2s 0 none of the above, my answer is _ Q Ce saneth rotates at angular velocity «in a uniform magretc eld (a) The emf (s) induced between the two ends of the rod is: Oreo Oi2per O12 Bet? (J none of the above, my answer is Q. A beam of 6.61 MeV protons is incident on a 77.4] tanget. The protons whch lide with tho target will produce the reaction 77.4] + p> 7/Si +n | Neglecting the recoil energy of Si, the kinetic energy of the emitted neutrons is (in MeV): O 20 O ase (1.50 O 250; () none of the above, my answer is Q: The electric potential energy of four identical point changes of magnitude Q = 5 pC placed at the comers of a square of side a = 30 om is (in Joules): 4 41 0) 30 {] 35 O ss 0 none of the above, ny answer is