Resistance in wire Flashcards
True or False. As you increase the length of a wire, the resistance decreases.
False. Increase in length of wire means increase in resistance.
What is the independent variable in this experiment?
- Length of wire
What is the dependent variabe in this experiment?
- Resistance
What is the control variable in this experiment? Give 3.
- Diameter of wire
- Material of wire
- Temperature of wire
Why do we add a resitor when experimenting how length of wire affects its resistance?
- To avoid high current
Why do we want to avoid a high current in this experiment?
- The temperature will change resistance
- Can cause burns
What is an alternative way to reduce current rather than using a resistor?
- Use lower cell voltage
Where do you put the piece of wire in this experiment?
- Put it on ruler
Vary lengths
What connects the wire to the circuit?
- 2 crocodile clips
True or False. Intervals of wire length should be increasing evenly.
Explain…
- True, this is so the graph is more accurate.
What is the relationship between resistance and the length of a wire?
- They are directly proportional.
What 4 factors affect the resistance of a wire?
- Length of wire
- Diameter of wire
- Material of wire
- Temperature of wire
Why does resistance increase when length of wire does? (3)
- There are more metal ions.
- So more collisions with electrons
- Electrons are harder to flow
Why does resistance decrease when the diameter of wire increases?
- More space for electrons to pass through
- Electrons = easier to flow
Why does the material of wire affect resistance?
- Different wires form different ions
- The more there are , the harder it is for electrons to flow. CONVERSE
What is meant by a zero error?
- A zero error is a reading on an instrument when the value should be 0.
True or False. A zero error can be solved by doing repeats.
- False. It is a systematic error
How does the crocodile clip not being exactly at 0 affect the results?
- This will mean that the distance you think the clip is at may be shorter/ longer.
How can I improve this practical, in terms of the 0 error?
- Subtract the 0 error from all distances.
What is the method of this practical (7)?
1.) Set up circuit - as shown
2.) Put ammeter in series w/ wire so it measures current
3.) Put voltmeter in parallel w/ wire so it measures the potential difference
4.) Start crocodile clip at 10cm
5.) Move crocidle clips by 10cm each time (swicth power pack off between readings.)
6.) Calculate resistance using v/I=R
7.) Plot graph and draw line of best fit
Give one safety note for this practical.
- Use resistor to avoid high current.
