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iGCSE EDEXCEL PHYSICS DISCUSSION 2012

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the new specification is ridiculous
spent 3 years learning stuff which doesnt matter and now i have to evaluate someones conclusion
wish i took igcses 2 years ago

anyway, can someone explain electromagnetic induction becasue i think something tlike that will come up tomorrow thanks :smile:

Reply 221

edex123

how do gas particles exert a pressure on their container when temperature is increased?

Reply 222

RoyalBlue7

How to find the frequency of a sound wave using microphone and oscilloscope? Hope that does come

This was posted from The Student Room's Android App on my Nexus One

Reply 223

black_cherries

So how was the exam everyone?
Did anyone else find the calculations hard?

Reply 224

Rss777

The exam was great ! It was much easier than I expected. Even the calculations werent too bad.

Reply 225

gdcf

It was okay, I messed up on the LDR question because I said that it was indirectly proportional however it wasn't. I put that the resistance decreases as the light intensity increases so hopefully I'll get a mark for that :smile:

Reply 226

RoyalBlue7

The MCQ question about skin burns and snow blindness. What the hell is snow blindness!!
I chose IR coz the specs says it causes skin burns but the actual answer is UV?
Hope they accept both because that was not testing our Physics

Reply 227

Relaxedexams

Original post by StUdEnTIGCSE

IR - Skin burns
UV - damage to surface cells and blindness

I chose UV but it might equally have been IR.

There will prolly be only one answer, not 2 :P

EDIT
"Snow blindness or photokeratitis, a type of temporary eye damage caused by snow reflecting UV light" - From Wikipedia

(edited 11 years ago)

Reply 228

RoyalBlue7

Original post by Relaxedexams

IR - Skin burns
"Snow blindness or photokeratitis, a type of temporary eye damage caused by snow reflecting UV light" - From Wikipedia

That means Skin burns is caused by IR and snow blindness by UV. Then they will have to accept both.

Reply 229

Relaxedexams

Original post by StUdEnTIGCSE

That means Skin burns is caused by IR and snow blindness by UV. Then they will have to accept both.

"UV from the sun causes sunburns and skin cancer. UV from other sources can also cause skin burns..."

Source:- http://ehsrms.uaa.alaska.edu/UVRadiationPADS.htm

I dont think that they would give us a question that had 2 possible answers. Anyway the question was only for 1 mark?

(edited 11 years ago)

Reply 230

gdcf

What did you guys do for the airplane one - the one about why they needed an extra power source or something? How did you work it out?

Reply 231

Coco406

Original post by gdcf

What did you guys do for the airplane one - the one about why they needed an extra power source or something? How did you work it out?

I didn't like that page because I don't know if I got it right or not :s-smilie:

I did like the equation for energy transfer or whatever which was at the front of the booklet and I got like 33333W and then I just said that that was more than 24kW so you would need extra power?

What did you do for the energy wind turbine question? With the power 78W and then you had to work out how much energy in 10s? Because it was 3 marks and we had already stated the equation above it!

Reply 232

Relaxedexams

Original post by gdcf

What did you guys do for the airplane one - the one about why they needed an extra power source or something? How did you work it out?

You had to find the energy given by the fuel cells using the equation : Energy=power * time

The GPE of the plane was 6000000 J, the energy that was calculated was less than that, therefore an extra power source was needed by the plane in order to meet the energy demand.

Reply 233

Coco406

Original post by Relaxedexams

I didn't do that! I found the power needed by dividing 6000000 by 180s (3 minutes) and it was more than 24kW so I said you needed an extra power source :s-smilie:

oops

Reply 234

Relaxedexams

Original post by Coco406

I didn't do that! I found the power needed by dividing 6000000 by 180s (3 minutes) and it was more than 24kW so I said you needed an extra power source :s-smilie:

oops

Energy provided by cells = 24000 * (3*60)= 4320000J

Energy needed = 6000000J

Energy provided by cells is less than 6m J therefore an extra power source is needed. (Energy is proportional to power)

EDIT:
What you did is right too. :biggrin:

(edited 11 years ago)

Reply 235

Coco406

Original post by Relaxedexams

Energy provided by cells = 24000 * (3*60)= 4320000J

Energy needed = 6000000J

Energy provided by cells is less than 6m J therefore an extra power source is needed. (Energy is proportional to power)

I get that yeah, but would it also be right to do

24kW= power source

Power= energy/time
Power= 6 000 000/180
Power= 33 333W

33 333W > 24 000W
Therefore extra power source is required?

Oh good! What did you do for the energy and turbine question?
Like 10s how much energy would be transferred?

(edited 11 years ago)

Reply 236

Relaxedexams

Yes, I thought you said there was no need for an extra power supply, my bad :P

Reply 237

Relaxedexams

Original post by Coco406

Oh good! What did you do for the energy and turbine question?
Like 10s how much energy would be transferred?

I think it should be :

24h = 78W
86400s = 78W
1s = (78/86400)W
10s = (78/86400)*10

But i didnt do that :frown:

I just used the equation: power=energy/time
Probably wrong cuz it is not worth 3 marks IMO

Reply 238

*Mariya*

what did you guys write for the last answer?-the question was to do with acceleration

Reply 239

Coco406

Original post by Relaxedexams

I think it should be :

24h = 78W
86400s = 78W
1s = (78/86400)W
10s = (78/86400)*10

But i didnt do that :frown:

I just used the equation: power=energy/time
Probably wrong cuz it is not worth 3 marks IMO

I think I did that but everyone said I did it wrong cos I got like 0.009J lol

Just I made really stupid mistakes in this paper so really want some reassurance for next wednesday!