Edexcel Unit 2: Physics at Work ~9th June 2014

I just realised that water absorbs microwaves after the exam. Surely this means that the microwaves wouldn't be reflected so there would be no way to work out how far they the rain was away or measure the speed?

Also, what mark do you think an A will be? I would say around 60/61

You can tell Edexcel are running out of ideas when the polarisation question is a picture of the front of the exam paper.

Yeah the lack of those questions annoyed me. That's the hardest part of the course, so I spent longest on it.

Ikr I was so good with electricity questions as well you could have thrown the most absurd diagrams at me and I would have been able to solve it!

Anyone remember why there must be a threshold frequency ?

the threshold frequency is the minimum frequency required by a photon to allow an electron to escape the surface of the metal (assuming the electron absorbs the photon). Below the frequency the electron does not have enough energy to escape the metal.

Threshold freq*h=work function

Nice, wrote that too
What did you put on the y axis?
I said energy in joules (j)


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Yeah I put kinetic energy in joules, I think they're correct

what about why the kettle wasn't 100% efficient (thermal energy)??

I think because when you did the calculation previous before you got 87% efficiency. So you could say not all the electrical energy (input energy) was converted into thermal energy ( useful energy). Maybe you could of commented on waste energy too being produced which would reduce the overrall efficiency. I wrote something along those lines

Isn't it energy in electron volts?

i put both, but you could put any i think as it is just two ways of measuring energy

I think because when you did the calculation previous before you got 87% efficiency. So you could say not all the electrical energy (input energy) was converted into thermal energy ( useful energy). Maybe you could of commented on waste energy too being produced which would reduce the overrall efficiency. I wrote something along those lines

Ok cool, I also put that some kettles have lights so some energy is transferred to light? Don't know if that will be on the mark scheme though haha

Naah bro, because that's a transfer 2 useful energy

Time to return - Calculate distance using t=s/v

Frequency - Doppler effect higher frequency return when rain is moving towards detector

Intensity - Higher amount of rain means more of pulse returned therefore greater intensity of return

I believe so, it's so it draws as little current as possible, I mentioned the resistors in parallel equation showing that (1/very large number) is basically 0 so it's negligible

I meant the transparent block that was placed on the 6PH02