1. Exploring The Multimeter
3/12/2014

2. Measuring Ohms with a multimeter
Set the multimeter to the Ω setting.
Bottom left make sure it is 2000 (with out the k)
Only Measure resistance when circuit is open – current flowing through a multimeter when it is set to ohms can damage it!
Simply put the multimeter probes to either end of the resistor and hold it there with your fingers.
Have patience. It can take some time for the reading to measure a steady number.

3. Now try it Test each of the four resistors used in lab yesterday.
Write down the ‘measured ohms’ in the final column

4. Measuring Voltage
3/12/2014

5. Measuring Voltage
Electricity flows through circuits because it is pushed by a force is called voltage. We measure voltage by setting the multimeter to its voltmeter position touching the two probes to the two sides of a component. The amount of voltage used by that component is reported as voltage drop.

6. How to use a Voltmeter
Turn the rotary switch three clicks counterclockwise to the 20-V Setting. The meter is now a voltmeter. At this setting the voltmeter can measure voltage between 0 and 20 V. The different settings can be used when measuring different voltages. The number stands for the maximum number of volts (or ohms or amps) you are trying to measure.

7. How to use a Voltmeter
Set up a circuit and close the switch. Voltage is always measured with current flowing through the circuit. Touch the two probes on the two sides of A component to measure its voltage drop. The red probe goes on the positive (+) side. Read the voltage drop across the component on the display.

8. Voltage Drop
The difference in the amount of voltage on the two sides of a component is what the voltmeter measures. The voltmeter measures the amount of voltage “used” by a component. The amount of voltage used by a component is its voltage drop. We always refer to the voltmeter reading as a voltage drop.

9. Voltage Lab

10. What to do now? In your groups – Start and finish today’s Voltage Lab
Continue to finish yesterday’s Resistor Lab
If you finish both labs, I want you to finish your homework assignments
If all is complete, help other groups finish their tasks.

11. Resistor/Voltage Relationship

12. How do you explain the voltage drop across a lamp in a circuit?

13. Voltage drop is like energy that gets used up Voltage drop is like the amount of push needed to get current through a component.

14. The Greater the resistance in series with a lamp, the dimmer the lamp glows.

15. ***** Important *****
Add a resistor to your investigation. Use black/black/black - - or 0-Ω resistance How could you make a resistor with 0-Ω of resistance? (The copper wire)

16. Class Data Use the 0-Ω resistor data - -
Lets compare our data as a class
Cross off the highest and lowest values.
Average all the values

17. Is there a pattern in the amount of voltage drop across the resistor?

18. Is there a pattern in the amount of voltage drop across the resistor?
The greater the resistance the greater the voltage drop across the resistor.

19. Is there a pattern in the amount of voltage drop across the lamp?

20. Is there a pattern in the amount of voltage drop across the lamp?
The greater the resistance, the less the voltage drop across the lamp

21. How do these voltages-drop patterns relate to the size of the resistor in the circuit with the lamp?

22. How do these voltages-drop patterns relate to the size of the resistor in the circuit with the lamp?
As the resistance increases, the voltage across the resistor increases and the voltage across the lamp decreases.

23. Add up the lamp and resistor voltages for each resistor
Add up the lamp and resistor voltages for each resistor. Is there a pattern?

24. Add up the lamp and resistor voltages for each resistor
Add up the lamp and resistor voltages for each resistor. Is there a pattern?
The sum of the voltage drops in the circuit equals the available voltage across the terminals of the battery.

25. Lab
Page 12 in your lab notebook