Why Does Current Flow Opposite to Electron Movement in a Cathode Ray?

[expscv]

i m studying cathode ray currently, but i was confised with the

idea of voltage and current flow

i recalled that voltage is a potential difference in a circuit, which allow current flow. but as i reseach on the interent there is some site talking about negative or positve volatge??

2. i remmber that when a voltage applied, a current will flow from positive to negative

but how come cathode ray is the opposite?

thanks

 

[JohnDubYa]

Consider two plates, one charged positive and the other charged negative. The difference in potential between the two plates is defined as the voltage. The potential is defined to indicate how much potential energy a charged particle would possesses if placed at the point where the potential is defined.

So a point having a potential of 200 volts indicates that a +2 coulomb charge would have a potential energy of 200*2 = 400 joules when placed at that point.

At another point the potential could be (say) -200 volts. In that case the +2 coulomb charge would have a potential energy of -400 joules.

So if the charge moved from the first point to the second point, it would move through a potential difference of 400 volts and lose 800 joules of potential energy in the process. (If there are no forces acting on the charge, it would then gain 800 joules of kinetic energy during the process.)

So we say that 400 volts of voltage exists across the two points.

(Yes, two coulombs of charge is ridiculously large, but I like to keep the math simple until the concepts are understood.)

A positive voltage (I am guessing, because the term is not well-accepted) would indicate movement from a point of low potential to a point of high potential. I would stay away from the concept of positive and negative voltage completely.

 

[M98Ranger]

for your help

Sure, I'd be happy to help clarify the concepts of voltage and current for you.

Voltage is indeed a potential difference in a circuit, which is measured in volts (V). It is a measure of the potential energy difference between two points in a circuit. This potential difference is what allows current to flow. Think of it as a water pump - the higher the voltage, the more potential energy is available to push the current through the circuit.

Now, regarding the concept of negative or positive voltage, it is important to understand that voltage is a relative measurement. This means that it is always measured between two points in a circuit. So, when we say a voltage is negative, it simply means that the potential energy at that point is lower compared to the other point. Similarly, a positive voltage means that the potential energy at that point is higher compared to the other point.

As for your question about the direction of current flow, you are correct that in most circuits, current flows from positive to negative. This is known as conventional current flow. However, in certain situations, such as in a cathode ray tube, the direction of current flow may be reversed. This is known as electron flow, where current flows from negative to positive. This may seem confusing, but it is just a matter of perspective and does not change the fundamental principles of current flow.

I hope this helps clarify the concepts of voltage and current for you. If you have any further questions, please don't hesitate to ask. Best of luck with your studies!