Gareth56

But if colour is described by the frequency of the radiation e.g. red is around 400nm and as such when this frequency of radiation impinges on the cones at the back of the eye is causes chemical changes in those cells; so I would suggest that colour perception is a physiological one also some people are colour blind in that they cannot perceive certain colours. I understood it that black was considerd to be the absence of colour hence the eye doesn't perceive any colour because all the frequencies of [visible] light are absorbed by the object, ergo, black is not a colour.

Is black a colour?

I've noticed that when I dissolve a soluble tablet in plain tap water the tablets dissolves quite quickly, however when I dissolve it in sparkling water it takes far longer. Any ideas why? Could it be due to the extra dissolved CO2 in the water that hinders dissolution?

Hartley Oscillator: http://en.wikipedia.org/wiki/Hartley_oscillator <-------- content means nothing to me I'm not an electrical engineer or an electronics engineer. Astable: http://en.wikipedia.org/wiki/Multivibrator<-------- content means nothing to me I'm not an electrical engineer or an electronics engineer. The response from insane_alien was what I was looking for not vague references to bits of kit followed by web references that are written for people who have a fairly good understanding of the subject of electronics. My question was was "how do these transformers get over the problem of DC not producing alternating magnetic fields?". Just giving references like those above wouldn't earn you many marks in an exam. However as I said thank you for trying.

There's no shame in not knowing how something works but thanks for trying

You just mentioned various transformers without explaining how they worked . My question was "So how do these transformers get over the problem of DC not producing alternating magnetic fields?"

So how do these transformers get over the problem of DC not producing alternating magnetic fields?

But this joke thing was only about 1.5" long buy say 0.5" thick. The transformers I've seen are dirty great big hulks of metal and plastic that need to be plugged into the mains. Also I thought that transformers worked only with alternating current. Even though direct current will create a magnetic field in the core [of the transformer] it will however not be a changing magnetic field and so no voltage will be induced in the secondary coil.

I know, but how did a small 1.5V AA battery produce such an unpleasant sensation?

I recall many years ago seeing a trick cigarette lighter which when you pressed the ignite button you got a shock and that only used a 1.5V battery; so how could that deliver a high voltage then?

How do get such a high voltage with such a low current?

How can I receive a 50kV electric shock (say via a taser) and not get killed?

So what's in the kettle that makes it "suck" more electrons from the wall socket than the lamp? Is it the resistance of the heating element? If so why does the resistance of the heating element of the kettle make the wheel of the meter spin faster than the filament of the lamp bulb? By the way, is the resistance of the heating element in the kettle greater or less than the filament in the bulb of the lamp?

Apologies for the vagueness. Let me try to elaborate. The voltage at the socket is the same [220-240V] irrespective of what the power rating of the appliance is that is connected to it. So if I plug in a 60W lamp the wheel on the meter spins relatively slowly and when I plug in a 2.5kW kettle is spins like hell. My question is why the difference in spin rates? Is the kettle drawing more current, i.e. electrons, from the socket than the lamp? If so why and how does the kettle "suck" more electrons from the wall socket? Hope that helps.

Why is it that when I switch on my 60W desk lamp the wheel in my electric meter spins fairly slowly but when I switch on my 2.5kW electric kettle it spins around like nobody's business. Presumably the potential difference at the wall socket is always 220-240V so is it something to do with the resistance of the appliance?

Thank you YT2095. So electrons are produced at the negative terminal (via redox half reaction) and travel through the external circuit to the positive terminal which has an excess of positive charge (again via redox reactions in that half cell). Meanwhile the conventional current is defined as the flow of positive charge from the positive terminal through the circuit to the negative terminal. Would that be a fair description?

"does a battery produce electrons at the negative terminal"?

The explanation of charge is I think complete, thanks. I'm still a tad confused regarding the question "does a battery produce electrons at the negative terminal"? Yes or No. If Yes do these electrons therefore flow from the negative terminal of a battery to the positive terminal despite the following: "The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction."

In College Physics (Wilson & Buffa) it states the following:- "Chemical processes involving the electrolyte and two unlike metal electrodes cause ions of both metals to dissolve into solution. Since they dissolve at different rates, and thus leave different excess electrons behind, one electrode (the cathode) becomes more negatively charged than the other (the anode). Thus the anode is at a higher potential than the cathode." Why is the anode (fewer electrons) at a higher potential than the cathode when the cathode contains more electrons? I would have thought that the electrode with the greater number of electrons would have been at the higher potential.

So are you saying [YT2095] that the high electric potential terminal (the +)of a battery produces electrons, due to chemical reactions within the battery(the electrochemical cell) which are then sent around the circuit?

Thank you swansont and YT2095 for your sensible and mature replies it's appreciated. When swansont says "the Charge is created by a chemical "imbalance" inside the battery itself." what exactly is Charge? Which is the main thrust of my question.

If a battery doesn't supply electrons or protons to a circuit but supplies "charge" which travels from the high potential (+) side of the battery, through the circuit ( e.g. a bulb), then finally to the low (-) potential side of the battery then what is this "charge" that the battery supplies? Thanks G56

OK, mist is beginning to lift So what do the units Js mean? I can fully understand what miles per hour or meters per second means but 'Joules second' is a tad mysterious.

Thanks but sadly our layman is just looking at you with a very very blank expression

If a layman were to ask what is Planck's Constant and what does the figure 6.626 x10^-34 Js mean how could you describe what it means?