The bandwidth of a network is commonly measured in terms of bitrate, which refers to the amount of data that can be transmitted over a network in a given amount of time, typically measured in bits per second (bps). Therefore, a higher bitrate generally indicates a higher bandwidth, allowing more data to be transferred simultaneously.
While frequency of waves is related to bandwidth in the context of wireless communications (e.g., the bandwidth of a channel can be determined by the frequency range it occupies), in a general networking context, it’s more common to refer to bandwidth in terms of data transmission rates.
Voltage and light levels are not direct measures of bandwidth in the context of network performance.
In summary, the most relevant measure of bandwidth in networking is bitrate, where higher values represent higher bandwidth capabilities of the network.