cceleration in One Dimension
PHYS 0212 DC Circuits
1
Direct Current (DC) Circuits
This experiment has four parts:
3. Construct a
Voltmeter
to measure voltage.
2. Construct an
Ohmmeter
to measure electrical resistance.
4. Measure the internal resistance of a galvanometer.
1. Construct an
Ammeter
to measure electrical current.
{
Using a
Galvanometer
Electrical charge is a fundamental property of matter, like mass, and may be
either positive or negative.
The unit of electrical charge is the
Coulomb
(C).
19
1.0 C
1.602
10
electrons
= −
×
Electrical
Current
(I) – The amount of charge flowing past a given point per unit
time.
Coulomb
Ampere (amp or A)
second
=
PHYS 0212 DC Circuits
2
Voltage
(V) – The energy per unit of charge.
Joule
Volt (V)
Coulomb
=
The Voltage and the Current are related by
Ohm’s Law
:
V
IR
=
R
= Resistance, units are:
Volt
Ohm (
)
Amp
=
Ω
A circuit is a closed path for electrical current.
+

1. Electrons gain potential energy in the battery.
2. They leave the positive end of the battery and
travel to the filament of the light bulb.
3. They lose potential energy in the filament by
converting it to light and heat.
4. The electrons return to the negative end of the
battery and gain more potential energy.
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cceleration in One Dimension
PHYS 0212 DC Circuits
3
+

V
R
A circuit is often drawn using a
schematic
– Lines represent wires and symbols
represent circuit elements.
I
I
V
IR
=
If the voltage of the battery is
V
= 1.5 V
and the resistance is
R
= 100
Ω
, what is
the current in the circuit?
V
I
R
=
1.5 V
0.015 A
100
I
=
=
Ω
15 mA
I
=
PHYS 0212 DC Circuits
4
Note that adding resistors
in series increases
the
effective resistance.
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 Spring '08
 Naples
 Physics, Current, Resistance, Resistor, Electrical resistance, DC Circuits

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