Different media are able to transmitted different volume of information per unit of time. This is usually measured in bits/second. Bandwidth only effected by the noise on the line.
1) Co-axial cable has higher bandwidth then twisted pair.
2) Fiber optic cable has a very high bandwidth.
When any information transmitted over a media, it is not possible to produced original signal level, as the signal transmitted some of the energy signals may be absorb by the transmation media.
1) Copper wire mostly and rapidly suffer from altenation.
2) Fiber optic can reduced altenation so regeneration is not required.
Similar to electrical resistance that resists the transmission of an electrical signal.
1) The higher impedence, the more energy is required to send an electrical signals.
Undesirable second signal, that is absorb by the medium and then super imposes itself on the original signal.