def finger_resistivity(L, Jmp, Sf, resistivity, wf, df, Vmp):
    """Return the fractional resistivity power loss in a finger (0 to 1)
    Given:
        L: finger length (cm)
        Jmp: currrent density at the max power point in A/cm2
        Sf: finger spacing (cm)
    """
    return L ** 2 * Jmp * Sf * resistivity / (3 * wf * df * Vmp) * 100.0
