Need to master Physics practicals. (1 Viewer)

[Forbidden.]

In both Physics and Chemistry, exam questions on practical or "first-hand investigations" often ask about accuracy, reliability and validity or the occasional safety procedures.

Physics practicals are generally safe right ?
(Except if you are running 50A across a wire in the motor effect practical....)
Otherwise safety glasses, a lab coat and gloves will be needed in case the silver nitrate's around (for Chemistry).

I barely know that accuracy is achieved when values are averaged using "±" and so on ...
Otherwise for reliability and validity my mind is pretty much blank.

What I'm asking is, how does one assess the accuracy, reliability and validity and maybe some safety procedures in Physics practicals in particular (e.g The Pendulum or Motor effect) ?

 

[watatank]

i'm sure there are better explanations on this but here's my take on reliability and validity...

reliability is getting the same results over and over pretty much, so you improve that by repetition

validity is a measure of how accurate/acceptable the results are in relation to your aim

for example, you are trying to calculate the speed of light by measuring how long it takes for a torch's light to travel across an oval. you could get the same answer by doing it again and again, its a reliable experiment, but does it make it valid?

 

[alcalder]

Actually, the radiation pracs - have to guard against radiation contamination AND the cathode ray tube pracs - those power supply thingies, they emit X-Rays.

Look here for the ultimate explanation on Accuracy, Reliability and Validity:

http://webs.mn.catholic.edu.au/physics/emery/accuracy.htm

 

[xiao1985]

Cathode ray is one expmt which you produce X-Ray, which may cause cancer if you are not careful (in addition to the high voltage)

 

[Forbidden.]

i'm sure there are better explanations on this but here's my take on reliability and validity...

reliability is getting the same results over and over pretty much, so you improve that by repetition

validity is a measure of how accurate/acceptable the results are in relation to your aim

for example, you are trying to calculate the speed of light by measuring how long it takes for a torch's light to travel across an oval. you could get the same answer by doing it again and again, its a reliable experiment, but does it make it valid?

The teacher said something VERY similar.

Actually, the radiation pracs - have to guard against radiation contamination AND the cathode ray tube pracs - those power supply thingies, they emit X-Rays.

Look here for the ultimate explanation on Accuracy, Reliability and Validity:

http://webs.mn.catholic.edu.au/physics/emery/accuracy.htm

That IS FANTASTIC ! Thanks very much !

Cathode ray is one expmt which you produce X-Ray, which may cause cancer if you are not careful (in addition to the high voltage)

Thanks for reminding me!
I eventually knew because apparently x-rays are caused when high-speed electrons convert their kinetic energy to photon energy at the anode at the point it strikes the anode.

 

[xiao1985]

Precisely.

And I believe it might have a systematic name called something like brumstrallung or something like that =/