Thursday, October 8, 2015

What is the resistance...


4. What is the resistance (R) of the resistor if the electric current (I) flowing through this resistor is equal to 2 A, and the electric potential (VL) on the left terminal of this resistor is 4 V and the electric potential (Vr) on the right terminal of this resistor is 10 V. Which is direction of the electric current through this resistor, toward left or right?
Vr - VL = ΔVr,l = -Ir,l R
-Ir,l R = (Vr - VL )

-Ir,l  = (Vr - VL )/R

Ir,l  = (VLVr )/R

 R = |(VLVr )/ Ir,l |

R  = |(4V – 10V )/2A| = 3 Ω

The electric current flows from greater potential, 10V, right, to the lower potential, 4V, left: toward to left.

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