Virtual Laboratory: Ideal Gas Law
Fourth Physics 102 Lab
Due May 9
Overview
In this experimental module you will be working with several aspects of
Ohms Law . The simulated environment is that of a circuit containing
resistors and voltage sources.
This simulation has opened in a separate window from the
text you are reading now.
Electricity is an apparent force in nature that exists whenever there
is a net electrical charge between any two objects.
Basics of Electrostatics:
- Electrical charges are either negative (electrons) or positive
(protons)
- The unit of charge, q , is called the coulomb.
- When there are equal numbers of positive and negative charges
there is no electrical force as there is no net charge. This is the
case for a neutral atom.
- Electrical force is created when electrons are transferred from
one material to another (e.g. rubbing a wool cloth with a plastic comb).
- Electrical charge is conserved; charge is neither created nor destroyed
Properties of Electricity:
CURRENT: denoted by I
and measured in amperes. Current flows from negative material to
positive material and is essentially the number of electrons per
second that are carried through a conductor.
VOLTAGE: Potential difference between
a negatively charged object and a positively charged one (like two
terminals on a battery). Potential difference is measured in units of
Volts ( V )which represents the work done per unit charge to move electrons
between the positive and negative terminals. If a potential
difference exists, then energy can be extracted.
RESISTANCE: Property of material
that helps prevent the flow of electrons in it. Metals are good
conductors due to low resistance. Wood is a poor conductor due
to high resistance. Resistance, R , is measured in ohms and
depends upon both the type of material and its size. Long wires have
more resistance than short wires; thin wires have more resistance than
thick wires. R is also temperature dependent.
OHM's LAW
Is there a relation between I, V, and R ? Let's
do an experiment:
In the circuit there is a battery (V), some resistors (R), and
a light bulb that can only be activated if the right number of amps reach it.
We can control this buy putting the right resistance in the circuit
for a given battery Voltage.
Experimental Instructions
First Experimental Procedure
- You have a bulb of unknown amperage. Drag the battery labelled
24 to replace the one labelled 12.
- Click on the switch to blow the light bulb up.
- If it blow up then everything is working fine.
- Now by trial and error drag resistors down onto the circuit
until the light bulb lights.
- Do the same procedure for the batteries of 6 and 18 volts.
- For each of the 3 Voltages determine the resistance in the
current that is required to light the bulb. Email the instructor
your solution for these resistances.
Now you should have experimentally determined Ohms Law.
Here are two circuits below. If
you know Ohms law you should be able to make the light come on
in one only one try as the amperage, I, is now specified.
Give it a try. Blown light bulbs represent a failure. If you
got one the first time or if the lamp didn't light then you
are not understanding the relationship between V, I and R.
Go back to the initial applet (in the detached window
and try again)
Now Go here for Part II