Unit 5, Day 9: Ohm’s Law Objective Question

How are voltage, current, and resistance calculated?

Opener

1. Review: define series circuit.

2. Review: define parallel circuit.

3. Review: what is resistance?

4. What is the relationship between resistance and current?

5. If the voltage in a circuit increases, what will happen to the current?

Voltage and CurrentStreamsrepresen

tCurrent

Snowcaprepresen

tsVoltage

Ohm’s Law

Using a MultimeterMeasuring

CurrentMeasuring

VoltageMeasuring Resistance

DefinitionThe flow of electricity

Electric potential energy

How difficult it is for current

to flow

Unit Amps (A) Volts (V) Ohms (Ω)

Black Wire COM COM COM

Red Wire 10A Input Input

Dial A V Ω

Setting DC DC -

Location of Probes

Across the open switch

On either side of battery or

bulb

Either side of resistor (not in

circuit)

Mystery Resistors Lab Build a simple circuit, using the

different colored resistors in place of a light bulb. Use only one resistor at a time. Your circuit needs a switch.

Measure current and voltage.

Calculate the resistance using Ohm’s Law.

Measure the resistance using the multimeter.

Resistor Current (A)Voltage Across

Resistor (V)

Calculated Resistance

(Ω)

Measured Resistance

(Ω)

Red

Green

Blue

Mystery Resistors: Analysis Questions

1. Did the measured resistance and calculated resistance match? Why or why not?

2. Which color resistor was it the most difficult for electricity to flow through? Use the word “resistance” to explain why.

3. Which color did the electricity move through most easily? Use the word “resistance” to explain why.

4. Relationship statement: as voltage increases, the current _________.

5. What is the relationship between resistance and current?