1. PHY 2049:Exam II The material consists of Ch. 26-29
Current and resistance
Circuits, Kirchhoff’s rules, junctions, loops and branches
Field effects, right hand rule
Field from – different sources. Right hand rule 2.
Problems from the book and old exams.

2. Review Session Exam II:Summer ‘08
Open office hours are in the afternoon:
The formula sheets cannot include questions and answers. No derivations are allowed.

3. A different problem
Electrons (mass m, charge −e) are accelerated from rest through a potential difference V and are then deflected by a magnetic field B that is perpendicular to their velocity. The radius of the resulting electron trajectory is:
A. √(2eV/m)/ B B. B√(2eV) /m C. √(2mV/e)/B
D. B√2mV /e E. none of these

5. Ch 27
A 18.0 Ω resistor and a capacitor are connected in series and then a 13.0 V potential difference is suddenly applied across them. The potential difference across the capacitor rises to 7.00 V in 1.50 μs. What is the capacitance in μF?
(1) 0.11 (2) 2.3 (3) 4.5 (4) 6.8 (5) 1.9
The voltage across an initially uncharged capacitor is V( t) = V0 ( 1 – exp [-t/ RC]) where V0 = 13 is the applied voltage. Rearranging yields; exp −1.5×10−6 / RC =1−V /V0 = Taking the log of both sides and solving for C yields C = 0.11 μF.

6. Figure shows five 5. 00 Ω resistors
Figure shows five 5.00 Ω resistors. Find the equivalent resistance between points (a) F and H and (b) F and G. (Hint: For each pair of points, imagine that a battery is connected across the pair.) a:
b: 3.125

7. What is i? All V = 10 Volts and all R = 4 Ohms

8. What is i? All V = 10 Volts and all R = 4 Ohms? What is j? What is k?

9. What is i? All V = 10 Volts and all R = 4 Ohmsj k
What is i? All V = 10 Volts and all R = 4 Ohms

10. R = 4 Ω, V = 4 V, what is the current through R?

11. R = 4 Ω, V = 4 V, what is the current through R?
8 = 4I => I = 2A