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A level Physics AQA - Electricity question - not sure how to do

Hi,
Am not able to do q06.1 and q06.2 from the Oxford Revise AQA A level Physics Study Guide, page104 of the book (if anyone has it).

Image of the question is below:

If someone could help me understand how they came to the answers of 06.1 and 06.2, that would be great. Explanation is needed.

(edited 10 months ago)

Reply 1

mosaurlodon

Well, 6.2 is just p=AR/L, for 6.1 im guessing they want you to show how this equation relates for constant 1cm intervals (ie area is constant) and how this determines the shape of graph.

Reply 2

Thomas_02

Original post by mosaurlodon

Well, 6.2 is just p=AR/L, for 6.1 im guessing they want you to show how this equation relates for constant 1cm intervals (ie area is constant) and how this determines the shape of graph.

Thanks, but the exam tip next to the question is - since density and length are constant for each cm so how are R and A related? Use this shape to predict the the shape of the graph.

The answer at the back of the book is - graph will be inverse of the shape of paper. When area is large resistance is small and vice versa.

So that’s why I am confused.

Reply 3

mosaurlodon

Oh yeah sorry then use that.
By the way p in this context means resistivity
P=ar/l
So if l and p are constant r is inversely proportional to a

Reply 4

LJZTGOOE

Original post by Thomas_02

Hi,
Am not able to do q06.1 and q06.2 from the Oxford Revise AQA A level Physics Study Guide, page104 of the book (if anyone has it).
Image of the question is below:

If someone could help me understand how they came to the answers of 06.1 and 06.2, that would be great. Explanation is needed.

mmmmh

Reply 5

Joinedup

I don't think the question explains what is going on very well.

if we say the probes shown in the diagram are measuring between 0cm and 1cm the next measurement will be between 1cm and 2cm and the measurement after that will be between 2cm and 3cm.

The area of the conductor is the thickness of the conductive paper into the diagram (constant) multiplied by the height (y direction ↕) of the conductive paper between the probe positions. the distance between the probes L is always 1cm ↔ for every measurement.

The resistance measured will be low when the height is large and the resistance will be high when the height is low - and that's probably all you can say about it before it gets over complicated

Reply 6

Thomas_02

Original post by Joinedup

I don't think the question explains what is going on very well.
if we say the probes shown in the diagram are measuring between 0cm and 1cm the next measurement will be between 1cm and 2cm and the measurement after that will be between 2cm and 3cm.
The area of the conductor is the thickness of the conductive paper into the diagram (constant) multiplied by the height (y direction ↕) of the conductive paper between the probe positions. the distance between the probes L is always 1cm ↔ for every measurement.
The resistance measured will be low when the height is large and the resistance will be high when the height is low - and that's probably all you can say about it before it gets over complicated