Current and Resistance

Key Questions

  • Answer:

    #V = I * R# or other forms...


    Ohm's law describes the relationship between voltage, current and resistance.

    It can be expressed in the form: #V = I * R# where #V# is the voltage (measured in volts), #I# the current (measured in amperes) and #R# the resistance (measured in ohms).

    This is also expressible in the VIR triangle:

    enter image source here

    which can be read as:

    #V = I * R#

    #I = V / R#

    #R = V / I#

  • A thicker wire (of the same material) has lower resistance.

    Having a thicker wire means that the volume of conducting material has increased so there are more conduction electrons available.

    A concrete example of this point would be consider the current that flows through a wire. Now take a second identical wire and set it parallel with the first. The current that flows through the parallel combination would be larger (by a factor of two). Therefore the resistance of that arrangement must be less than the single wire (half the resistance of the single wire).