Bellwork (2/26) What do voltage sources do in a circuit? They do work on charges that is transferred into electric potential energy. Aside: High voltages can do a lot of work on each charge it encounters

This Week’s Lab [Title, Name & Period] 2/26/14

Background Information [ On the formula cards ] Ohm’s Law Equation Electric Power Equation

Purpose: To learn how to use a multimeter. To determine the relationship between voltage, current, resistance and electric power.

Hypothesis: What do you think will happen to the current in a circuit as you increase the resistance? (Write out the question and answer it.)

Materials: Multimeter 8 resistors 2 alligator wires 1 D-cell battery

Procedures: [ The drawings and settings for each part of the lab ] Part 1 – Finding Voltage Part 2 – Finding Resistances Part 3 – Finding Current

Procedures:

Procedures: Part 1 - Finding Voltage 1.Set the multimeter to the setting as in the diagram 2.Touch the probes to both sides of the battery 3.Record the results

Procedures: Part 2 - Finding Resistance 1.Set the multimeter to the setting as in the diagram with the probes connected to the ends of a resistor 2.Record the result in the data table 3.Repeat steps for all 8 of the resistors

Procedures: Part 3 - Finding Current 1.Set the multimeter to the setting as in the diagram with the wires connected to a resistor and battery 2.Record the result in the data table 3.Repeat steps for all of the resistors

Data Table: Current and Resistance Battery Voltage: Resistor Label Resistance (Ω) Current (mA)Power (W)

This Week’s Lab - Day 2 [Title, Name & Period] 2/27/14

Bellwork (2/27) What two new equations were given yesterday? * Mr. Z. will check off the H.W.

Bellwork (2/27) What two new equations were given yesterday? “Ohm’s Law” and “Electric Power”

Settings PART 1 PART 3 PART 2

Data for the Lab Make sure connections are secure. Record all sig. figs. If multimeter reads “1. ” for a current (part 3) it means overload put a line in your data table. Please turn off multimeters when done to save the batteries.

Calculations: (convert mA to A) [ Power 7 total in T-Charts add to table] Graphs: [two total – use mA for current] *title *on graph paper *numbers *units *best fit curve *** current (y) vs. resistance (x) *** power (y) vs. current (x)

Conclusion: [In paragraph form, minimum 6 sentences.] Identify all variables as: independent, dependent, or controlled. Use your data to determine if your hypothesis was correct. What are some sources of error? Explain what the graphs mean. Explain how this lab supports (or doesn’t) Ohm’s law and the electric power equations. (Hint: look in the textbook.)

Rubric Title / Purpose:(4) Hypothesis / Materials:(8) Data:(5) Calculations (7): (14) Graph:(14) Conclusion: (20) Order (5) Total =70