# Why the amplification?

1. Feb 25, 2010

### samreen

for a classical oscillator. i kno when resonance happens. what i dunno is WHAT happens in resonance. and WHY it happens. im very sketchy bt the details...is resonance happening when the system is oriented or configured to b able to absorb max energy? why the amplification? could u suggest reading material?

2. Feb 25, 2010

### netheril96

Re: resonance

Make sure you know how to solve second-order linear ODE with constant coefficients
If not,don't bother to think why

3. Feb 26, 2010

### samreen

Re: resonance

ive dun the math...for free, damped and forced. trouble is, it feels like math.not physics. wich is what ive asked.

4. Feb 26, 2010

### Studiot

Re: resonance

I agree wholeheartedly. a Physicist should be able to explain most things without resort to complicated maths.

Try this: Either as a thought experiment or a real one.

Hang a very heavy weight to act as a pendulum.
Take your handkerchief and tie a knot in the end.
Attack the pendulum with your knotted kerchief by hitting the weight repeatedly with the knot, always in the same direction.

You will find that if you strike at random intervals, the pendulum will scarcely move.
If however you always strike at the same point in the motion of the pendulum the blows will add up and the oscillatory motion will increase.
Eventually you will be able to get a good steady swing going.

This is resonance (at very low frequency so you can see what is happening).
The weight is accepting small packets of energy at its resonant frequency. All these packets are reinforcing one and other so energy transfer is high.
You can also upset the oscillation by striking at the wrong moment - when the pendulum is going towards the knot. Do this enough times and you will slow or stop the oscillation.
If you want to demonstrate damping in this experiment use a piece of sponge rubber on a string. The sponge will introduce damping.

5. Feb 26, 2010

### Bob S

6. Feb 27, 2010

### samreen

Re: resonance

thanx guys...makes a load of sense now