Soln7 - DC Circuits

# Soln7 - DC Circuits - 8B Worksheet Answers 7. DC Circuits...

This preview shows pages 1–4. Sign up to view the full content.

8B Worksheet Answers 7. DC Circuits 1. Series Circuit a) b) I batt = I 1 = I 2 c) V batt = V 1 + V 2 d) P batt = P 1 + P 2 e) P batt = I batt V batt = I batt V 1 + I batt V 2 = I 1 V 1 = I 2 V 2 = I 1 2 R 1 + I 2 2 R 2 = P 1 + P 2 R eff = 18 Ω I batt = 5 / 9 A P 1 = I 1 2 R 1 = 50 / 27 W P 2 = I 2 2 R 2 = 100 / 27 W P 1 + P 2 = 50 / 9 W P batt = I batt V batt = 50 / 9 W = 5.556 W Parallel Circuit a) b) I batt = I 1 + I 2 c) V batt = V 1 = V 2 d) P batt = P 1 + P 2 e) P batt = I batt V batt = I 1 V batt + I 2 V batt = I 1 V 1 = I 2 V 2 = I 1 2 R 1 + I 2 2 R 2 = P 1 + P 2 R eff = 4 Ω I batt = 5 / 2 A P 1 = V 1 2 / R 1 = 50 / 3 W P 2 = V 2 2 / R 2 = 25 / 3 W P 1 + P 2 = 25 W P batt = I batt V batt = 25 W

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2. Left Circuit a) R eq = 2 R I batt = V batt / 2 R b) Junction Rules: I 1 = I 2 + I 3 A Loop Rules: V batt - I 2 (4 R ) = 0 a - I 3 R - I 3 (2 R ) - I 3 R + I 2 (4 R ) = 0 b Solving Equation b gives I 2 = I 3 b Plugging b ’ into A gives I 1 = 2 I 2 A Solving a gives I 2 = V batt / 4 R a Plugging a ’ into A ’, finally, gives I 1 = V batt / 2 R , (which is what we found in part (a)), so I 1 = V batt / 2 R I 2 = V batt / 4 R I 3 = V batt / 4 R Right Circuit a) R eq = 15 R / 8 I batt = 8 V batt / 15 R b) Junction Rules: I 1 = I 2 + I 3 A Loop Rules: V batt - I 2 (4 R ) - I 2 R = 0 a - I 3 R - I 3 (2 R ) + I 2 R + I 2 (4 R ) = 0 b Solving Equation b gives I 3 = 5/3 I 2 b Plugging b ’ into A gives I 1 = 8/3 I 2 A Solving a gives I 2 = V batt / 5 R a Plugging a ’ into A ’, finally, gives I 1 = 8 V batt / 15 R , (which is what we found in part (a)), so I 1 = 8 V batt / 15 R I 2 = V batt / 5 R I 3 = V batt / 3 R
3. a) 12 bulbs b) 8 bulbs c) The parallel arrangement will result in the lowest effective resistance, and so the highest current. The power delivered by the battery is IV , so a higher current will result in a greater power, which will drain the battery’s energy fastest. d)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 10/16/2010 for the course PHYS 8B taught by Professor Catherinebordel during the Spring '10 term at University of California, Berkeley.

### Page1 / 5

Soln7 - DC Circuits - 8B Worksheet Answers 7. DC Circuits...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online