I know that resistors are used to limit the value of the current flowing in a circuit. But why is the value of current the same before it enters the resistor and after it leaves it? I do understand that it creates a congestion for current flow. But why do they have the same values?
In the above circuit, the value of current flowing Between \$B\$ and \$C\$ is 0.5 Ampere, and the value of the current flowing between \$C\$ and \$D\$ is also 0.5 Ampere. Why and how is it that they are equal? Shouldn't the current flowing between \$B\$ and \$C\$ be greater than that flowing between \$C\$ and \$D\$?
Thanks in advance.
Best Answer
Current is the flow of charge.
simulate this circuit – Schematic created using CircuitLab
Figure 1. The water circuit analogy.
A simple water circuit analogy might help. In Figure 1b the battery is represented by the pump. The resistor is represented by a restriction in the pipework - in this case a radiator panel.
It should be clear that the water current is flowing in a loop. What goes into the radiator at the top comes out at the bottom and returns to the pump. Similarly in the electrical circuit the current that goes in at the top of the resistor comes out at the bottom and returns to the battery.
So water current is analogous to electrical current. Water pressure is analogous to electrical voltage.
Don't push the water analogy too far!
First of all, apologies for thinking you were a beginner and pitching my answer a bit low. It was the PixelPaint edited image in your OP ...
I think you've got this mostly right. \$ V_d \$ will depend on electron mobility which will vary with the conductivity of the material. Watch out for materials with negative temperature coefficients too.