I'm doing a piece of A-level physics coursework at school at the moment and seens I do Maths as well this shouldn't be hard for me, but I just can't get my head around it. So, any help would be really apprieciated!(adsbygoogle = window.adsbygoogle || []).push({});

For my coursework, I'm testing different materials for sound-proofing and then looking at the structure of the material - seeing which works best and why.

One side I have a signal generator with a speaker set a set distance away from a microphone and an oscilloscope (that measures the potential difference, or the voltage). In between the gap I insert materials and measure the change in the voltage (for example, with just air in the gap I recieved a reading of 20mv, when cardboard was inserted it dropped to 10mv).

After my first practical I realised a problem...I didn't even think to take into account the thickness of the material, and they were all of different thicknesses! I spoke to my Teacher about this and he came up with the idea of using an equation using logs to find a constant that would over come this problem.

He said:

He said that plotting the Voltage (from the material) against thickness would result in an exponential curve and hence you could state:

Vm = Vo x e^(-ct)

Where Vm is the voltage from a material (the reading), Vo is in air, c is some unknown constant and t is the thickness.

He then took logs (simple enough):

lnVm = lnVo - ct

lnVo = lnVm + ct

Then apparently you can plot lnV against t to get a gradient, which is C.

Could someone please explain how you get from that final equation to plotting that graph? And also how I would reapply the answer with the constant to my old data to form the new more exact data.

Thanks, Rich.

Sorry about the long read!

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# Homework Help: Problem Involving Exponentials (Sound)

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