Recent content by beckett

Hi, I'm looking into electromagnetic radiation at the moment and something has just entered my head. If its true that an electron will not radiate unless its velocity changes with time then could this property be used to determine absolute rest. That is, how can we know that if something is...

Folks, thanks for your help, i think I've got it now, these forums are so useful.

I guess the thing that confuses me is the following equation: If if have a system wherein i transmit a power of 4dBm to an antenna, there is a loss of 6db in the transmission line and a gain of 18dBi then the following applies: EIRP = Pout - Ct + Gt = 16 dBm This to me suggests that an...

Hi, I'm having difficulty understanding how the gain of an antenna works. I appreciate that the gain effectively concentrates the available RF energy into a narrower beam but i can't fathom how this seems to mean that if i have a transmitter transmitting at say 100dBm that i can use antenna...

russ_watters: Thanks for the reply. I'm slightly confused when you say that voltage is essentially constant along a wire. What is a piece of wire if not one big long resistor/series of resistors. If its the internal resistance that provides the problem then if we use a 'wire' that is...

Hi folks, Sorry for this second post so quick but its bugging me! I have been reconsidering some fundamentals of electrics and have opened a can of worms for myself (thanks Cliff for closing the lid on the previous one). If i consider again a simple closed DC circuit consisting of a wire and...

Cheers, that makes perfect sense, so in a way would you say my assumption was correct i.e. raising the resistance does increase the power output but doing this in reality means current is reduced and hence the apparent paradox is you can't raise the resistance AND maintain the current, all other...

Hi folks, Please, please help me, i know the answer to my question must have an easy answer but i can't figure it out. Consider a simple circuit with a piece of copper wire, a switch and a battery. I know that when i close the switch the PD drives the electrons around the wire at a rate...

Sorry folks, looks like the ASCII art didn't come out as i had drawn it. Have a look at the attached image if your interested, cheers.

Hi folks and happy new year, As usual i have been leafing through some old physics books and have stumbled across something that has confused me, wonder if you can help. Having looked at a 'classical' graph of interatomic potential energy against distance within a solid and how it relates to...

Hi folks, quick question, i have just read a small snippet on data transfer that has sparked some thoughts. Basically it was this: Baseband transmission, one carrier frequency is used and the electrical signal is applied directly to the wires. Broadband transmission, signal is sent by...