Complex sentence: Electronic noise is often measured in volts per root hertz\\ left (V\\ cdot Hz ^\\ right): doubling the bandwidth of the measurement doubles the power level measured, but voltage is proportional to the square root of power.
Split into simpler sentences: Electronic noise is often measured in volts per root hertz\\ left (V\\ cdot Hz ^\\ right). This term is derived from the fact that doubling the bandwidth of the measurement doubles the power level measured, but voltage is proportional to the square root of power.