Transcript Lesson 7 - Measuring Voltage Drop and Current

Measuring Voltage Drop and
Current
 Electricians
often measure the
voltage and current in a circuit to
make sure the circuit is working
properly.
HOW DOES A VOLTMETER
WORK?


A voltmeter is used to measure the
“voltage drop” in a circuit.
Voltage drop refers to the amount of
energy lost or gained between two points
in a circuit.



Voltmeters are connected to circuits in
parallel.
The positive portion of the voltmeter
(known as the positive terminal) is
attached to the positive side of the circuit.
The negative terminal of the voltmeter is
attached to the negative side of the
circuit.
Example of a circuit with a
voltmeter:

In this example, the voltmeter is connected in
parallel to the cell (battery). The voltmeter
would read that the battery produces 1.5V.
HOW DOES AN AMMETER
WORK?


An ammeter measures how much current
passes through the circuit.
An ammeter is connected in series in a
circuit.
Example of a circuit with an
ammeter:
Connecting Both a Voltmeter and
an Ammeter


When building circuits, it is also possible
to wire them with parts that are wired in
series and parts that are wired in parallel.
Let’s take a look at some examples:
Example 1:

Create a circuit with 3 cells, a closed
switch, two light bulbs wired in series, and
2 light bulbs wired in parallel. Connect a
voltmeter across the cell and connect an
ammeter between the second and third
light bulbs.
Example 2

Create a circuit with four cells, an open
switch, a TV, clock, and a light bulb wired
in parallel. Connect an ammeter between
the TV and clock and connect a voltmeter
across the light bulb.
Classwork/Homework


Complete the practice questions on the
handout provided to you
Circuit Continuity Worksheets