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# Physics Quantitative OCR Question watch

1. It is suggested that the relationship between 1/I and x is:
1/I = (ρ/AV)x + k

where ρ is the resistivity of the wire, A is the cross-sectional area of the wire, V is the potential difference of the power supply and k is a constant for the circuit..
Using the value for the gradient and your other results determine a value for the resistivity ρ with an appropriate unit.
￼￼￼
Does anyone know how to answer these type of questions? I have my coursework tomorrow. All I know is that it has something to do with y = mx +c
2. (Original post by Elhamm)
It is suggested that the relationship between 1/I and x is:
1/I = (ρ/AV)x + k

where ρ is the resistivity of the wire, A is the cross-sectional area of the wire, V is the potential difference of the power supply and k is a constant for the circuit..
Using the value for the gradient and your other results determine a value for the resistivity ρ with an appropriate unit.
￼￼￼
Does anyone know how to answer these type of questions? I have my coursework tomorrow. All I know is that it has something to do with y = mx +c
In general, this type of question requires you to linearise the suggested relationship.

Ex.
you need this to be a straight line so you can find out the mass by measuring the gradient. So you plot kinetic energy on the y-axis and v^2 on the x-axis.

For your equation you need to pick something for y to equal and something for x to equal. Then the gradient will be resistivity (or some multiple of it).
3. (Original post by lerjj)
In general, this type of question requires you to linearise the suggested relationship.

Ex.
you need this to be a straight line so you can find out the mass by measuring the gradient. So you plot kinetic energy on the y-axis and v^2 on the x-axis.

For your equation you need to pick something for y to equal and something for x to equal. Then the gradient will be resistivity (or some multiple of it).
How would I work out the units required using my equation?
4. (Original post by Elhamm)
How would I work out the units required using my equation?
Units for what? To work out units you can use the rules

• both sides must have the same units
• any time you add two quantities, they must have the same units (you can't add metres to kilograms)
5. (Original post by lerjj)
Units for what? To work out units you can use the rules

• both sides must have the same units
• any time you add two quantities, they must have the same units (you can't add metres to kilograms)
For finding resistivity.
I tried solving this equation but I was still unable.
can you please show me how to work it out step by step using any example figures for y-axis, x-axis and gradient??
6. (Original post by Elhamm)
It is suggested that the relationship between 1/I and x is:
1/I = (ρ/AV)x + k

where ρ is the resistivity of the wire, A is the cross-sectional area of the wire, V is the potential difference of the power supply and k is a constant for the circuit..
Using the value for the gradient and your other results determine a value for the resistivity ρ with an appropriate unit.
￼￼￼
Does anyone know how to answer these type of questions? I have my coursework tomorrow. All I know is that it has something to do with y = mx +c
What do I and x stand for?

Assuming that you have measured: I, A, V, and x for some experiment the way to check if your relationship is true is to construct a graph which should be a straight line.

Straight lines are in the form y=mx+c
your's is in the form (1/I)=(some numbers)x+k

do you see the similarity?
7. (Original post by lerjj)
What do I and x stand for?

Assuming that you have measured: I, A, V, and x for some experiment the way to check if your relationship is true is to construct a graph which should be a straight line.

Straight lines are in the form y=mx+c
your's is in the form (1/I)=(some numbers)x+k

do you see the similarity?
I stands for current and x stands for the lenght of the wire
8. (Original post by Elhamm)
I stands for current and x stands for the lenght of the wire
Ok, basically what you have to do is choose something for y to equal and something for x to equal when you plot your graph- in this case you would most likely plot 1/I on the y axis and x on the x axis.

Look at your function and see if you can tell what the gradient and y intercept of the resulting line will be.

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Updated: February 1, 2015
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