Part C
Part B
Project 20
Batteries in Series
Build the circuit, set the meter (M5) to the 5V setting, and turn on the slide switch (S1).
Part A:
Read the battery voltage on the meter. If your batteries are new then it should
be about 4.5V.
Part B:
Remove the left battery in the holder (B3) and move the end of the red jumper
wire to touch the left spring in the holder. Read the voltage on the meter; measuring 2
batteries.
Part C:
Now also remove the center battery and move the end of the red jumper wire
to touch the center spring in the holder. Read the voltage on the meter; measuring 1
battery.
NOTE:
The accuracy of your meter may vary.
What voltage did you measure in Part A?
What voltage did you measure in Part B?
What voltage did you measure in Part C?
5V
When batteries are connected in series, they add together, making
the total voltage higher. An AA type battery is rated at 1.5V, but
brand new ones will be up to 1.6V, and they get weaker as they
are used up.
In Part A, the battery holder (B3) has three 1.5V type AA batteries
in series, so the battery voltage is about 4.5V (1.5V + 1.5V + 1.5V
= 4.5V).
In Part B, you are measuring two 1.5V type AA batteries in series,
so the voltage is about 3V (1.5V + 1.5V = 3V).
In part C, you are measuring one 1.5V type AA battery, so the volt-
age is about 1.5V.
Part A
Use the preceding circuit, but replace the
meter (M5) with the lamp (L4). Compare the
lamp brightness with 3 batteries (Part A), 2
batteries (Part B), or 1 battery (Part C).
Does the lamp brightness change like the
voltage does (are they proportional)?
Your L4 lamp is designed to be
used at 4.5V; lower voltages like
1.5V or 3V do not get the bulb’s
filament hot enough to produce
light as well. See project 29 for
further explanation of this.
Project 21
Lamp at Different Voltages
If a circuit is given too much voltage
then its components will be damaged.
It is like having the water in your faucet
come out at higher pressure than you
need, and it splashes all over the
room. If water in a pipe is at too high
of pressure then the pipe may burst.
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