hi just wondering if you knew the answer to this q that has been bugging me... it asked you to draw the resistance against current graph for a filament lamp... one of the marking points was that it should be non zero... how can there be resistance when there is no current?
hi just wondering if you knew the answer to this q that has been bugging me... it asked you to draw the resistance against current graph for a filament lamp... one of the marking points was that it should be non zero... how can there be resistance when there is no current?
The filament lamp will have a resistance at the beginning when there is no current, let's say X. As you add current, the filament heats up and your resistance then changes with current.
Think about it: any component will have resistance whether or not current is flowing through it, because it is a property of the component. If you were to draw a graph of the resistance of a fixed 5 ohm resistor against current, would you start with your resistance at 0 or will it be a horizontal line through 5? Same logic applies here, just that, now, our resistance is changing
Okay i'm new to this website and since i haven't found any other thread for the upcoming exams i'm gona just through my questions here.......i have attached an image below which is taken from a model answer sheet , can anyone please explain to me why the answer is C??...I find both C and D to have both vector and scalar quantities..!!!...what am i missing here?
Okay i'm new to this website and since i haven't found any other thread for the upcoming exams i'm gona just through my questions here.......i have attached an image below which is taken from a model answer sheet , can anyone please explain to me why the answer is C??...I find both C and D to have both vector and scalar quantities..!!!...what am i missing here?
Remembering that a vector is a quantity with an ascribed direction and a scalar just has a magnitude,
A: is force a scalar - does, for example, a pushing force not have direction?
B: does time have a direction?
C: this is right as we know, because time has no direction and velocity does
D: does mass have a direction or is that weight? And is velocity a scalar?
The filament lamp will have a resistance at the beginning when there is no current, let's say X. As you add current, the filament heats up and your resistance then changes with current.
Think about it: any component will have resistance whether or not current is flowing through it, because it is a property of the component. If you were to draw a graph of the resistance of a fixed 5 ohm resistor against current, would you start with your resistance at 0 or will it be a horizontal line through 5? Same logic applies here, just that, now, our resistance is changing
The filament lamp will have a resistance at the beginning when there is no current, let's say X. As you add current, the filament heats up and your resistance then changes with current.
Think about it: any component will have resistance whether or not current is flowing through it, because it is a property of the component. If you were to draw a graph of the resistance of a fixed 5 ohm resistor against current, would you start with your resistance at 0 or will it be a horizontal line through 5? Same logic applies here, just that, now, our resistance is changing
Hiya! I'm really stuck on this q and I would really appreciate it if you helped out Three identical cells, each of resistance R, are connected in series, with an external resistor in series which also has a resistance of R. The current in the external resistor is I. If one of the cells is reversed in the circuit what is the new current in the external resistor.
I have tried to find the electromotive force for the normal circuit... E= V +Ir So E= IR + 3IR SO E=4IR if you connect one of the cells opposite then the total electromotive force is surely 8/3 IR as that's 2/3 of the original electromotive force... Let x be the new current so... 8/3IR = x*R + x*3R (I'm assuming that even though the polarity has been reversed, the resistance still remains) This gives you with 2/3 I but the answer is 1/3 I and I just don't understand why ((
Yo babes, whats up with the new physics specification? Is it any different to previous years?
yh it definitely is. thats why you need to have the spec at hand or have it atleast book marked on your laptop. so that you learn what they want you to learn and then practice these topics.