hi i was wondering if anyone could help me. i am doing my last piece of gcse coursework for science - physics:
How does the diameter of a wire affect its resistance? ( and therefore area)
does anyone know what to put in the prediction like what should happen?
and what factors do i need to keep the same and why? like temperature, length of wire, amount of electricity passed through the wire. etc
does anyone know any others, thankyou
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ohms law watch
- Thread Starter
- 10-03-2004 20:19
- 10-03-2004 20:24
Consider the analogy of a current of water flowing through a pipe full of footballs. The voltage is the force used to push the water in between the footballs, and the footballs provide a resistance trying to slow down the current.
Now what do you expect to happen to the resistance of the wire when it is made thicker? Easier to push the electrons through, or harder? Bear in mind the voltage is constant, so if it becomes harder to push the electrons though, for example, the current will decrease. What do you think will happen if you make the wire thicker?
- 10-03-2004 20:26
If you increase the diameter, you increase the cross sectional area of the wire. This will cause the resistance to decrease, cos the electrons have more room in which to flow.
You've gotta keep other factors that affect the resistance constant, cos if you didn't, you'd wouldn't be able to investigate the effect of increasing the diameter on the resistance; the other stuff would contribute.
If you increase the temperature of the wire, the atoms in it will vibrate more. This will make it harder for the electrons to flow through.
Increasing the length of the wire means the electrons have a longer distance to travel - obviously it's easier to travel a short distance than a long one.
- 10-03-2004 20:27
the smaller the cross sectional area - the higher the wires resistance.
temperature effects the path of electons inside a metal - the more atoms are vibrating in a metal - the more the path of the electron is obstructed.
The material involved (and how pure it is) also affects resistance.
- 10-03-2004 20:39
Damn it... I was trying to make her think rather than just giving the answer! You'll never learn like that.