Use of Resistors?

You should go for basics to know the purpose of resistor.Start from voltage/current sources.

Well every load is designed for particular voltage / current and resistors are helpful in that. You can take the example of SRIM in which full resistance is there at starting and is cut out in steps to increse speed. In DC drives aramature and field current is controlled with the help of resistors. The list goes on.

1. Resistors are the "real" bit of complex numbers used for circuit calculations Z = R + jX etc
2. But they often represent losses(or transfered energy) in circuits, even though the losses are really magnetic or optical or mechanical and the circuit is an analog.
3. They have sneaky uses like representing the actual radiation from a radio antenna, rather than its losses in heat. Or the shaft power of a motor, which disappears electrically in a "resistance" but appears as mechanical power.
4. Sometimes they appear as negative values, as in "tunnel diode" microwave oscillators.
5. Did you ask the prof what he considered an "unreal" use of a resistor?
   

Dear Lester, As a new student in electrical studies myself... I have found that resistors are most often used as voltage dividers. In other circuits they are applied as current limiters, and lastly they are used to convert electrical energy into heat. I have never heard the term "Modulate" used with resistors. -Good luck in your studies

Resistance modulates voltage !!!!!!!!!!!!!

Didn't hear before..

They make pretty good heaters.

"Sophomore" -is that from the Greek? And would an Ancient Roman have spelled "Jester" as "lester"?

anyway..thank you for the help guys.. im from Philippines and im not a Greek xD Sir 67model ahaha amm...i would like to somehow briefly explain what i mean by resistors modulating voltage. resistors modulates voltages by wasting the energy into heat. it modulates or adjust the voltage in the sense that, not all devices can take too much voltages(it might destroy the device) that is why resistors are made...the explanation i've given was based on my understanding on what my professor and readings are saying

OK, I accept you as Lester, not Jester. There seem to be questions on CR4 which could be answered by search of Wikipedia or the web. Often in that case, it is difficult to separate a genuine philosophical question from a nuisance - but they are usually short and tell little about the questioner!

A resistor is anything that opposes the flow of electrical current. In doing so, there is a potential (voltage) difference across that resistor that can be defined by Ohm's Law equation V = I*R.

In real life, everything has some degree of resistance to electrical current, some materials more than others. Electrical wires and cables are resistors, generally of pretty low resistance and thus little opposition to current flow or little voltage drop. Insulators have very high resistance, so that only extremely low current can flow through them.

There are other effects that grow out of this, including those due to a current in a coil of wire, the current in semiconductors with different chemical impurities that effect the numbers of excess electrons or electron vacancies, and others.

But when you come down to it, the basic essence of the "use of resistors" is to allow electrical current to flow in a circuit, with the result of a voltage that occurs across the resistor.