How are physical signals sent over copper wire?How are physical signals sent over fiber-optic cable?

What will be an ideal response?

This is, once again, a reiteration, but it is an essential item for understanding the chapter contents.Electric voltage is used to send signals over copper wire, alternating between no voltage on the line and small, fixed voltages (usually between –2.5 V and +2.5 V depending on the standard).In fiber-optic cable, the signal is sent by the presence or absence of light.In MMF, you need lasers to focus light at a particular angle through the cable; in SMF, you only have one signal, so cheaper options like specialized LEDs are an option in addition to lasers.