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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
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.
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.
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
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.
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.