resistor_worksheet

resistor_worksheet - fl Ql‘l_(§h§fl; Electric...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

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

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: fl Ql‘l_(§h§fl; Electric Circuits Ph 5112 Winter 95 The circuit we will study today is shown in the figure. For our orientation I have marked some points with the letters A through F. The four resistors have the values F E R1=SOOQ R2= 10009 R3 = 1000 (2 R4 = 1500 Q The goal is to answer the following questions R4 Find the total current, I, and the total resistance, R. What is the voltage across R4 (V4) ? What is the current through R2 (12) ? — D A B C a Solution 1: the experimental approach a Voltmeter is used to measure the voltage ( =Jpotential difference) between two points of an electric circuit. Question I : Where in our circuit would yen connect a voltmeter to measure the battery voltage? Measured voltage (V): a Amperemeter is used to measure the current through a circuit element. To connect an amperemeter you have to break the circuit and insert the meter. Question 2: Where in our circuit would you measure the total current? Measured current (1): Question 3: Find the total resistance R: Question 4: Describe the measurement of V; the voltage across resistor R9 ) I 1 measured value: 4 Question 5: Describe the measurement 0%, the current through resistor R151 I i measured value: Solution 2: the theoretical approach we need a few basic laws, rules and equations Ohm’s Law can be applied to each element of the circuit, for example V2 = 12 R2 We usually ignore the very small resistance of connecting wires. Consequently, every point on the same wire is at the same voltage. Question 6: Which points (A - F) in our circuit are at the same voltage? Loop Rule (Kirchhoff) energy is conserved which simple means that if you go around a in a complete circle, the net change is zero. For an electric circuit this means: the sum of all voltage changes in a loop is zero mm W Question 7: Write down all voltage changes for the loop ABEF. Wire Battery 3—] i—b from a to b + from b to a Resistor ——-|/\/V\J—- in current direction I 9 against current direc. Question 8: What is the current 11 ? Just assign a direction If the value you calculate for this current is positive, you picked the right direction Ifthe value comes out to be negative, you picked the wrong direction Junction Rule (Kirchhoff) , charge is conserved: What goes in must come out! the sum of the currents at a junction is zero Question 9: Assign your current directions and write down the (current) equations for the junctions at B, C, D, E Resistors in Series: Question 10: Apply the Loop Rule to circuit a) Question I 1: Apply the Loop Rule to circuit b) Solve for R = Parallel Resistors: When-k l' ° \/ .L R R1 3 R ' + I i V - A: Find the total Resistance Rm: R1 R4 Analyze the circuit and start with the innermost series or parallel sub—Circuit. In our case, this is resistors R2 and R3 in parallel. R3 What is the combined resistance R23? It helps to re-draw the diagram with the first sub-circuit replaced by the combined resistor (R23 in our case) What is the next element to process? R4 - 9 What IS R234 . R23 Here is the new diagram. What is the total resistance? R234 B} Find the total current I: in: s C} Find V4, the voltage across R4: Apply Ohm’s law to R4: V4 = R4 I4 R4 is given so we only need 14. How does 1.; compare to 1234, the current through R234? V Rtot Find [2342 51:1 Find V4: V23: V33 :13 R23 Find V; and 12, the current through R2: ...
View Full Document

This note was uploaded on 06/03/2011 for the course PHY 112 taught by Professor Beacom during the Spring '11 term at Ohio State.

Page1 / 3

resistor_worksheet - fl Ql‘l_(§h§fl; Electric...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online