Mr. Fleming

D4. Explain the relationship among voltage, current and resistance in a simple series circuit.

What are the factors that affect how electrons move along a wire?

Static electricity: electricity involving a build-up of stationary charges.

Current electricity: electricity involving the flow of e- through a material.

Voltage, current and resistance are all related to each other by a formula called Ohm’s Law, developed by George Simon Ohm in 1827.

Current = Volts/ Resistance I= V/R

Current: rate at which electrons move past a point in a wire.

Measured by using amperes or amps (A)

Voltage: the difference in electrical potential between two points.

Measured by using Volts (V)

Voltage provides the force or push that moves electrons through a wire.

An increase in voltage causes an increase in electron flow.

Resistance - opposition of a substance to a flow of electrons.

Measured by using Ohms (Ω)

The higher the resistance; the lower the current.

Material Thickness of a wire

Length of a wire

Temperature

Power is a function of Voltage and current expressed by the equation.

P = I x V

Power: The rate at which energy is transferred or used in an electrical circuit.

Measured by using Watts (W)

Steps to solving Word Problems:

1. Read the problem

2. List all known values with their units

3. Write out equation with unknown isolated

4. Plug in #’s with units

5. Solve, give answer with PROPER UNIT!

Current = Volts/ Resistance

I= V/R

Power is a function of Voltage and current expressed by the equation.

P = I x V

What is the current passing through a 3

resistance that is connected to a 12

volt battery?

12 volts/3 ohms= 4 amps

A 30 amp current is passing through a 4 resistor, what is the

voltage in the circuit?

30 amps x 4 ohms= 120 volts

A 6 v battery pushes electrons through a

circuit with a current of 0.3 amps, what is the

resistance of this circuit?

6 volts/ 0.30 amps= 20 ohms

A 12 v battery causes a 0.3 amp current to pass through a bulb.

A) What is the bulb’s power usage?

B) What is the resistance of the bulb?

A. 12 volts x 0.3 amps= 3.6 watts

B. 12 volts/ 0.3 amps= 40 ohms

A.) How much current passes through a 40 W bulb attached to a 120 v power source?

B.) What is the resistance of the bulb?

A. 40 watts/ 120 volts= 0.33 amps

B. 120 volts/0.33 amps= 363 ohms

A. A 100 W bulb has a 0.2 amp current passing through it, what is the voltage of the power source?

B. What is the resistance of the bulb?

A. 100 watts/ 0.20 amps= 500 volts

B. 500 volts/0.20 amps= 2500 ohms

Name 2 factors or things that affect current?

Voltage and Resistance

How are resistance and current related to each other?

Amps= Volts/ Ohms Ohms= Volts/Amps