What are we doing Today?Chapter 5 (Ohm’s Law)

**Hand in Extra Assignment Prepare for the lab Do the lab Complete the lab write up Hand in the formal lab for

Monday

OHMS LAW

What is ohms law?

- Ohm’s Law explains the relationship between voltage (V), current (I) and resistance (R)

- Used by electricians, automotive technicians, stereo installers

VOLTAGE (V)

-It is the push or pressure behind current flow through a circuit, and is measured in (V) volts. 

CURRENT

Current refers to the quantity/volume of electrical flow. Measured in Amps (A)

RESISTANCE

 Resistance to the flow of the current. Measured in Ohms

Chart

Ohm’s Law

Voltage Current Resistance

V I R

V = Voltage (Volts = V)I = Current (Amperes = A)R = Resistance (Ohms = Ω)

General Rule.

1.  Assuming the resistance does not change:

As voltage increases, current increases.as voltage decreases, current decreases.

2.  Assuming the voltage does not change:

As resistance increases, current decreases.

As resistance decreases, current increases.

What can we use to measure?

Multi meters/ DVOM

Resistors

Why do we need resistors

To decrease the amount of voltage applied to a component

The value of the resistor is marked on the body using coloured rings

Resistors

Resistor color chart

Different types of circuit Series circuit : One pathway for current to flow. Example: Old Christmas lights

Parallel Circuit More then one path way for current

to flow. Used in most electrical vehicle

circuits.

Series and Parallel Circuits

12

E8 – lesson 4E9 – lesson 4

Voltmeter

Dependent & Independent

The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the effect on the dependent variable is observed and recorded.

For example, a scientist wants to see if the brightness of light has any effect on a moth being attracted to the light. The brightness of the light is controlled by the scientist. This would be the independent variable. How the moth reacts to the different light levels (distance to light source) would be the dependent variable.

Real data

In reality, the data we get is not the same as what we get in theory.

Why?

Because when we calculate numbers in theory, we are dealing with an ideal system. In reality there are sources of error in every aspect, which make our numbers imperfect.

Now go have fun!