HELP in physics paper 6!!

[Igcian3]

Hey guys..I wanted to ask about how to draw the curve (straight line or smooth curve)for graphes and how to get the gradient( i have looked at the mark scheme which said that we had to use triangle method !)! what is a triangle method ?!! :%) also there is a question in nov 2010 61 q 3c ..I donnot know how to estimate the resistance !! http://www.xtremepapers.me/CIE/Cambridge IGCSE/0625 - Physics/0625_w10_qp_61.pdf

 

[xIshtar]

Triangle method is simply what you do in maths. Picking two points on the line, and forming a triangle and using the equation. y2 - y1 / x2 - x1 if you get what I'm saying. If it's a curve, you may have to draw a tangent to estimate the gradient.

To draw the curve, simply plot you points, and trace the pattern a couple of times without actually drawing it. Once you are happy that it will be relatively smooth, then you draw it. As for question 3c, I will have a look now

 

[haochen]

first u find the last R which is 10.1
the read the question.......
they said current will be 0.5 so multiply it with 0.3 to get 0.15
the check for the resistance which is the one u calculated 10.1 (from the table)
it was a tricky question that took me time to think when i solve

hope u got it

 

[xIshtar]

first u find the last R which is 10.1
the read the question.......
they said current will be 0.5 so multiply it with 0.3 to get 0.15
the check for the resistance which is the one u calculated 10.1 (from the table)
it was a tricky question that took me time to think when i solve

hope u got it

Huh, I didn't get what you said. If you multiply current by 0.3 you get 0.15, I get that, but how is the resistance 10.1, the markscheme said 10...

I did get 10.1 too, but a different way.

Basically, I did V=IR

Which implies 0.15(10.1 + X) = V

But from the initial reading in (a), you know that V is also equal to 0.25X

Equating them to each other gives 0.25X = 1.515 + 0.15X
Which gives 0.15X = 1.515

Which finally equates to X = 10.1 Ohms..

Please explain your method haochen, as mine would waste valuable time in the exam ):

 

[haochen]

u first solve the previous part to get the answer then u can continue solving the second part.
10.1 shud be the answer when u find the resistance of 0.15 A.
then follow the thing on the previous post.

hope u get it

 

[xIshtar]

u first solve the previous part to get the answer then u can continue solving the second part.
10.1 shud be the answer when u find the resistance of 0.15 A.
then follow the thing on the previous post.

hope u get it

Still slightly confused. I have found the 10.1 value for 0.15A current, but isn't the total resistance in the circuit at that point X+10.1? I don't understand how you arrived at 10.1 just by multiplying by 0.3