Lesson 2

1 What did you do last time? 2 multimeter negative electrons positive charge voltage PRINT the word next
to the image on the next slide.
3
Electronics1 - L2 cha pos ele vol neg mul
4 You can measure when a battery is new,
but do you know which batteries will still work
even though they are no longer new?
You are beginning to master
an important tool -- the multimeter!
battery bands test leads The LED is
a ONE WAY PART.
The longer wire on the LED
must connect to the POSITIVE
(+) TERMINAL
on the battery.
black/red
alligator
leads
LED To find out,
you will need:
multimeter
5 2 1 The LED
will be dim,
even with
a new battery.
Measure and record
the voltage of each
USED battery.
Connect the LED
to that USED battery and
record if the LED lights.
Estimate the minimum voltage needed to light the LED.
You will need a darkened place to see the dimmest LED flicker.
Repeat steps 1-3
on the previous
class (slide 23)
to measure
the voltages.
6 Are the minimum voltage requirements different for different components? (yes)
The minimum and maximum voltages needed for a particular electronic part
are usually specified by the manufacturer online or in a printed catalog.
Locate the electric motor and buzzer in your kit.
Test to see if some
of the used batteries
will work with the
motor or buzzer,
even though they
didn’t light the LED.
The buzzer is
a ONE WAY PART.
The RED wire
must connect to the POSITIVE
(+) TERMINAL
on the battery.
4 3
7 To find out, locate: If you connect two batteries together end to end,
what will be the total voltage?
Congratulations! You now know how
to measure the voltage of a battery!
2 new batteries
of the same type
(AA, AAA, C or D)
(not in the kit)
1 red
2 black
alligator leads
LED multimeter
test leads
2 battery bands
8 Batteries in series ADD their voltages. Connect
the plus end
of one battery
to the minus end
of the other.
Measure the voltage
of each battery.
Now connect
the two batteries
together in series.
Now measure
and record the voltage
across both batteries.
How does the voltage
across two batteries
compare to
the individual
battery voltages
2 3 1 Click for answer.
9 Is the LED brighter
than it was with one battery?
Connect the LED
to the two batteries
in series.
REMEMBER:
The longer wire
from the LED
connects to the positive battery terminal.
4
10 Now use your multimeter
(refer to Class #1, Slide 23)
to measure the voltage across
each of these three circuit components.
Position the red and black test leads, as shown.
Record the voltage in the book or on paper for each component.
The LED may be difficult to see,
with only one battery.
1 3 2 volts volts volts
11 You are measuring the voltage
supplied by the battery.
The battery is a
CONSTANT VOLTAGE SOURCE.
What did you observe?
Did you notice that despite the different components
-- the voltage was ALWAYS THE SAME?

What are you actually measuring
in these “one component” circuits
Click for answer.
12 What do you notice? 1 2 1. across the LED
2. across the buzzer
3. across BOTH

RECORD each voltage.
LED


BUZZER


BOTH
Connect these components together
in one big loop.
This is called a SERIES circuit because all the components
are linked together
in a SERIES,
one after the other.
You may want
to try two batteries
instead of one!
Use your multimeter
to measure the voltage
across each component
on this circuit:
13 What do you observe A VOLTAGE DIVIDER! Click for answer. The TOTAL voltage across the battery is SPLIT or
divided between the buzzer and the LED.

This SPLITTING of the voltage between components connected in series is called . . .
14 Dividing Voltage! FIRST click on Electra below. AFTER she finishes,
click on the red button.
You can hit pause at any time or replay to start over. 1. 4 volts
2. 2 volts
3. 8 volts
15 Voltage Divider A more advanced explanation of voltage dividers (optional).
Here "potential difference" is another term for voltage.
NOTE: ONE VOLT is defined
as ONE joule of energy per electric charge of ONE coulomb. 1V = 1J/C.
You can leave these details for later or explore them now.
Part Battery


Bulb


Motor
Symbol
16 Which charged particle flows in wires What is the unit of measurement for voltage What type of current comes from a battery How do the voltages
combine when batteries
are connected in series
1 2 3 4 5 When components are wired together
in series, do all parts get the same voltage
the voltages add together electrons a volt DC or direct current Not necessarily! They do make a voltage divider!
17

Introduction
Lesson 1
Lesson 2
Lesson 3
Lesson 4
Lesson 5
Lesson 6
Lesson 7
Lesson 8

Resources

 



Complies with NGSS:

NGSS 3-5. Engineering Design
3-5-ETS1-1, 3-5-ETS1-2, 3-5-ETS1-3

Core Disciplinary Ideas:
ETS1.A Defining and Delimiting Engineering Problems
ETS1.B Developing Possible Solutions
ETS1.C Optimizing the Design Solution

Engineering Electronics: Voltage, Current and Resistance