Electricity confuses me. I have two TV sets connected to one cable. They can be tuned to different channels at the same time with no problem. They tell me at the cable company that
up to four TV's will work fine even with four different stations.

I have four telephones connected to one telephone line. If you talk on one, nobody can use the others. I also have a computer hooked to that line. When it's on line, the phones don't work. My new printer has a fax machine and it answers every call after the third ring and won't let me talk on the phone until it assures itself that the call didn't come from another fax.

My answering machine doesn't answer until the 4th ring, so it won't work unless I unplug the printer.

I looked at the cable TV coax and it has a single conductor surrounded by a grounded shield. The telephone wire has four insulated conductors.

My question is why can't the telephone with four wires do what the TV cable does with one?

Another electrical problem: A light bulb has a resistance wire that produces more light and a little heat. An electric heater has a resistance wire that produces heat and a little light. How does that wire know?