1. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Todays Circuit Draw the following circuit. 1)What is the potential difference across the power source? 2)What will happen if the switch is opened? 3)Which ammeter will have a greater current reading: the red or the green?

2. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Ohms Law and Graphing

3. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola calculating Resistance Use: R = V I V R I to complete the table on page 2 of your handout.

4. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Graphing Resistance 2) Plot a graph of potential difference (y-axis) versus current (x-axis) What are the coordinates for the two points? A(0,0) B(20,6) What is the difference in the y coordinates between A and B? RISE 6 – 0 = 6 Volts What is the difference in the x coordinates between A and B? RUN 20 – 0 = 20 Amperes SLOPE = RISE = 20 RUN 6 SLOPE = 3.3 OHMS B A

5. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Recap 1)Plot the points, and draw a line of best fit. 2)Pick two points on the line 3)Figure out the coordinates of the two points. 4)Determine the RISE (Δy, or VERTICAL DISTANCE) between the two points. 5)Determine the RUN (Δx, or HORIZONTAL DISTANCE) between two points. 6)Calculate slope, with SLOPE = RISE RUN 7) CAUTION: Watch the units!!!

6. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Calculating Resistance 5) Make the calculations necessary to complete the table. What do you notice? 6)Graph it! V R I

7. Graphing Resistance

8. 8)

9. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Calculate Slope! 1)Pick two points on the line 2)Figure out the coordinates of the two points. 3)Determine the RISE (Δy, or VERTICAL DISTANCE) between the two points. 4)Determine the RUN (Δx, or HORIZONTAL DISTANCE) between two points. 5)Calculate slope, with SLOPE = RISE RUN

10. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Graphing Resistance A B What are the coordinates for the two points? A(0,0) B(0.04,6) What is the difference in the y coordinates between A and B? RISE 6 – 0 = 6 Volts What is the difference in the x coordinates between A and B? RUN 0.04 - 0 = 0.04 A SLOPE = RISE = 6 V RUN 0.04 A SLOPE = 150 OHMS

11. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola Next class: Quiz! (5 minutes) You will be doing a Lab on Ohms law –Read investigation 10-11 (page 320) in your textbook

12. Wed. Nov. 28, 2007 SNC1D | Miss. Manaktola