Register to reply 
Graph of 1/R against E/V 
Share this thread: 
#19
May614, 05:15 PM

Emeritus
Sci Advisor
HW Helper
PF Gold
P: 7,819

Now it's making more sense. I'll try to get back to this soon. In the meantime, someone else may jump in. In your circuit, the battery itself is usually modeled as an ideal voltage source providing emf, E, in series with a resistor, having (usually small) resistance, r. Thus the equation: E = IR + IrThe R is whatever you used, R_{1}, R_{2} , ... , R_{2} + R_{3}, ... 


#20
May614, 05:22 PM

P: 1

Yh i have my test tomorrow on the 7th May. AQA Physics Unit 03X task 3.



#21
May614, 06:52 PM

Emeritus
Sci Advisor
HW Helper
PF Gold
P: 7,819

Take ## \ E=IR+Ir \ ## and divide by ##\ IR\ .##



#22
May714, 05:24 AM

P: 10




#23
May714, 08:27 AM

P: 1,988

Yes, the slope of the curve is the internal resistance.



#24
May714, 02:50 PM

Emeritus
Sci Advisor
HW Helper
PF Gold
P: 7,819

It strikes me as kind of a strange way to combine two (or is it three?) very common quantities. Substituting in other orders can make it very difficult to see this result. 


#25
May1314, 03:10 AM

P: 58

No. I don't believe you can deduce the internal resistance from that gradient.
gradient = EMF/V by 1/R (IR + Ir) / IR = 1 + r/R (1 + r/R) x R = R+r given the gradient is a constant, however the sum of the two resisitances (R+r) the total resistance of the circuit is not constant. I don't see how this can be accurate? 


#26
May1314, 05:04 AM

Sci Advisor
Thanks
PF Gold
P: 12,261

Given that 'internal resistance' is not Ohmic over the whole range of currents, it is considered to be, in most situations. When it isn't, you don't get a straight line graph. 


#27
May1314, 12:48 PM

P: 58

your right im completely wrong, I took the same exam today, luckily I realised before I answered the question.



#28
May1314, 12:49 PM

P: 58

I couldnt see that all you needed to do was factor out the 1/R as x



Register to reply 
Related Discussions  
Does amputated connected graph in Peskin's book is same as the irreducible graph?  High Energy, Nuclear, Particle Physics  7  
Drawing the angular velocity graph from the acceleration vs. time graph?  Introductory Physics Homework  5  
How to do velocitytime graph to distance graph/acceleration to velocity graph?  Classical Physics  1  
Manipulating inverse square graph into straight line graph  Introductory Physics Homework  4  
Real life situation to a sin graph on position by time graph  Differential Equations  6 