Resistance in wire

Question 1

True or False. As you increase the length of a wire, the resistance decreases.

Answer 1

False. Increase in length of wire means increase in resistance.

Question 2

What is the independent variable in this experiment?

Answer 2

• Length of wire

Question 3

What is the dependent variabe in this experiment?

Answer 3

• Resistance

Question 4

What is the control variable in this experiment? Give 3.

Answer 4

• Diameter of wire
• Material of wire
• Temperature of wire

Question 5

Why do we add a resitor when experimenting how length of wire affects its resistance?

Answer 5

• To avoid high current

Question 6

Why do we want to avoid a high current in this experiment?

Answer 6

• The temperature will change resistance
• Can cause burns

Question 7

What is an alternative way to reduce current rather than using a resistor?

Answer 7

• Use lower cell voltage

Question 8

Where do you put the piece of wire in this experiment?

Answer 8

• Put it on ruler
  Vary lengths

Question 9

What connects the wire to the circuit?

Answer 9

• 2 crocodile clips

Question 10

True or False. Intervals of wire length should be increasing evenly.
Explain…

Answer 10

• True, this is so the graph is more accurate.

Question 11

What is the relationship between resistance and the length of a wire?

Answer 11

• They are directly proportional.

Question 12

What 4 factors affect the resistance of a wire?

Answer 12

• Length of wire
• Diameter of wire
• Material of wire
• Temperature of wire

Question 13

Why does resistance increase when length of wire does? (3)

Answer 13

• There are more metal ions.
• So more collisions with electrons
• Electrons are harder to flow

Question 14

Why does resistance decrease when the diameter of wire increases?

Answer 14

• More space for electrons to pass through
• Electrons = easier to flow

Question 15

Why does the material of wire affect resistance?

Answer 15

• Different wires form different ions
• The more there are , the harder it is for electrons to flow. CONVERSE

Question 16

What is meant by a zero error?

Answer 16

• A zero error is a reading on an instrument when the value should be 0.

Question 17

True or False. A zero error can be solved by doing repeats.

Answer 17

• False. It is a systematic error

Question 18

How does the crocodile clip not being exactly at 0 affect the results?

Answer 18

• This will mean that the distance you think the clip is at may be shorter/ longer.

Question 19

How can I improve this practical, in terms of the 0 error?

Answer 19

• Subtract the 0 error from all distances.

Question 19

What is the method of this practical (7)?

Answer 19

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

Question 20

Give one safety note for this practical.

Answer 20

• Use resistor to avoid high current.