QUIZ 22 CH.22 |
SELECTED DISCUSSIONS TO exercises/problems
BELOW.
YOU ARE RESPONSIBLE FOR ALL PROBLEMS EVEN THE ONES WITHOUT DISCUSSIONS, WHICH ARE DESIGNED TO HELP YOU DO RELATED EXERCISES. Each sublist is separated by a semi-colon ";" and ends with the name of the section for those exercises. WE WILL REVIEW THEM IN-CLASS THE LAST WEEK BEFORE FINAL EXAM. |
CH. 22: SEE LECTURE NOTES: |
CH. 22 MULTIPLE CHOICE TBA - Exercise/problems 1, 3, 5, 11, 12, 13, 19 |
TURN IN: 1, 3, 5, 11, 12, 19 |
* DISCUSSIONS PROVIDED. |
1. SEE LECTURE NOTES: In a resistor, the current I and voltage V_{R} are in phase: I_{m} = V_{Rm}/R, where voltage across R is V_{R} = V_{Rm}*cos wt and I = V_{R}/R. I_{rms} = I_{m}/(1.41..), where 1.41... = square root of 2. Note also that I_{rms} = 0.707*I_{m} . |
3. (a) wL = 1/(wC) Solve for w. (b) Plug in numbers; evaluate wL or 1/(wC) numerically since they are equal. |
5. I_{m} = V_{Lm}/(wL), where V_{Lm} = 12.0 (V). |
11. Use equation 22.18. V_{rms}^{2 } = V_{Rrms}^{2} + (V_{Lrms} - V_{Crms})^{2} , where V_{rms } is the rms value of voltage source. The other rms voltages are given. Evaluate and take the positive square root to get the rms voltage source value. |
12. Use the formula for impedance Z on page
745, equation 22.22, and set C = infinity, effectively removing C
from the formula.
Z^{2} = R^{2} + w^{2}L^{2}. Set w = 2*pi*120 rad/s, where pi = 3.14...and solve for Z. With this value of Z, set (2Z)^{2 } = R^{2} + w' ^{2}L^{2} , where w ' is the new frequency doubling the impedance. |
13. Use Z^{2 } =
R^{2} + (wL - 1/wC)^{2 }
. (a) Plug in the 3 values of w given and evaluate Z in each case. (b) I_{m} = V_{m}/Z, where Z is the total impedance for the RLC series circuit and V_{m} and I_{m} are the voltage source and current amplitudes. Plug in the 3 values of w given and evaluate I_{m} in each case to answer the question. (c) Use equation 22.23. (d) Draw a diagram of the phasors (vectors) like that on page 7 of LECTURE NOTES. The lengths of each voltage vector (phasor) can be easily scaled in your diagram since they are given by V_{Rm} = I_{m}*R , V_{Lm} = I_{m}*(wL), and V_{Cm} = I_{m}*(1/wC) =(1/ wC)*I_{m} . |
19. See section 22.5 and page 8 of LECTURE NOTES . |