Download series resistors

What we will do today
• Investigate resistors in series.
• Define a formula for the total
resistance of resistors in series.
Combining resistors (Read)
• We are now going to investigate the
effect of three resistors in series.
• What apparatus will be needed?
• What will our circuit diagram look
like?
Resistors in Series
• We will measure three resistors
separately and then measure them when
combined:
• Resistance is measured using an ohmmeter.
Resistor
R1 (10 )
R2 (22 )
R3 (47 )
RT (combined)
Resistance ()
Resistors in Series
• From our results we can see that the total
resistance, RT, is the sum of all resistors in
series.
• We can express this as a formula:
• RT = R1 + R2 + …
• The total resistance is ALWAYS bigger
than the biggest resistor.
Example 1
•
•
•
•
RT = ?
R1 = 100 Ω
R2 = 200 Ω
R3 = 150 Ω
Example 2
•
•
•
•
RT = 15 Ω
R1 = 6 Ω
R2 = ?
R3 = 4 Ω
What have we learned today?
• For a series circuit:
• RT = R1 + R2 + …