How can I identify the contents of three sealed boxes(A,B and C)each with terminals at both ends(read details)

Question

A contains nothing, B contains a piece of resistance wire between the terminals and C has a working diode. I was thinking running current through them and see what happens to an attached light bulb but I don't know what results would be caused. Can someone please help me with this?(it is schoolwork)

Answer 1

do your own home work you lazy git

Answer 2

When you say "nothing", do you mean a piece of conductive wire? Or do you really mean it contains nothing?

In any case, the easiest way would be to use an ohmmeter.

The box with the resistive wire would read as a resistance.
The box with the diode would read as an open circuit one way and as a near-zero resistance the other way.
The box with a conductor would read near-zero resistance both ways (if you meant the box contained no conductor, it would read an open circuit both ways).

If you cannot use an ohmmeter, then a bulb would work... you would have to guess as to the resistance of the box by how bright the bulb was. Obviously an open circuit would be easy to detect: the bulb would be off.

Answer 3

The solution with this question lies with the Diode. (since i'm sure that's probably the item you don't know anything about) Read up on what a Diode does and the solution should be obvious to you.

Answer 4

Astound your science teacher, impress your colleagues etc Here's how:
Wire up each box in series with a lamp then in parallel to a power signal generator set to low (<20Hz)
A= bulb permanently off
B=bulb on
C=bulb flickering at f/2 Hz

Answer 5

Hi. You have good answers. A diode only allows current to flow in one direction (below a certain voltage). http://en.wikipedia.org/wiki/Diode

Answer 6

You're on the right lines.....Not going to give you the whole answer though. Look for A being brighter than B and C will be............