- How will you make sure this is a fair test?
- When you change your independent variable (Length of wire), What do you think will happen and why? You must include scientific reasons.
- A step by step explanation of how to do the experiment including all your amounts, concentrations, measurements and safety.
- Explain why you have chosen this method, relate this to your background scientific Information.
We done an experiment in Physics, and we basically connected an ammeter, voltmeter, Battery, leads, croc clips, a piece of wire - to make a circuit. We placed the piece of wire in a tray of water to make sure it didn't overheat.
oh and how do you divide the volume of gas by the time to give your initial reaction rates? :\
I really need a good grade in this.
any help appreciated.
thank you.
Does changing the length of a wire affect it's resistance?
First, you did an experiment in physics, not done one.
%26quot;We did a physics experiment%26quot; is the easy way to write it.
The resistance of a wire is quoted per unit length, like 0.1 Ohms per meter or 2 Ohms per 100 meters.
Putting twice the length of the same kind of wire into a circuit puts twice the resistance into the circuit from the wire.
You can get the same result by using the same length of wire as originally, but using wire with twice the resistance per meter.
To make an experiment, you have to control all the conditions so everything is the same for each test except for the variable element.
For a resistance experiment you need to make sure the voltage applied to the circuit is the same every time and the ammeter is accurate over the range of values you are going to measure.
You have to use components for the circuit that can handle the amount of voltage you are going to use.
Using a low voltage is safer then using a high voltage.
Everything in the circuit must be isolated from anything it's not supposed to touch.
The places where components in the circuit are connected must be clean to get a good connection, and the connections must be safe and strong enough to be reliable.
That means both the electrical and mechanical quality of the connections must be of a good standard.
To find out if resistance depends on the length of wire there are two ways to do it.
1....You can cut different lengths of wire, measured accurately, and put each length into the circuit one at a time and note the reading of the ammeter each time.
2.... You can use a long piece of wire and have a connector like a crocodile clip on another piece of wire to connect to the resistance wire at different places along it's length and note the reading of the ammeter each time. You will need a ruler or measure some marks along the wire so you know how much wire is in the circuit each time
That is how variable resistors work, which are also called potentiometers.
This is about resistors.... scroll down to read about variable ones . . .
http://www.solarbotics.net/bftgu/startin鈥?/a>
If you are measuring volumes of gas they have to be at the same pressure, otherwise you have to calculate what the volume would be using the formula
P1 over V1 =P2 over V2
where P is the pressure and V is the volume.
That means you have to measure the pressure and volume each time.
That assumes the gases are at the same temperature when you measure them, which they normally will be because they will be at room temperature.
You can use a manometer to measure it, and when the volumes are known, all corrected to the same pressure, you can divide the volume by the time in seconds or minutes.
20 ml in 10 minutes = 2.00 ml per minute
32 ml in 15 minutes = 2.13 ml per minute
As a reaction proceeds it normally gives out heat which warms the reactants and increases the rate of reaction. Some reactions absorb heat so the reactants get cooler.
Does changing the length of a wire affect it's resistance?
Resistance of a metal is proportional to length and inversely proportional to area.
R = constant x length/area.
all conductors have resistance
if you have long wire it has more resistance
