I thought the Medical Physics Paper was quite nasty, especially that trigonometry question on the eye. Hoping boundaries for that are slightly lower hopefully 58 or 59/60 for an A*? Here's the question if anyone can help figure this out.

Two bright point sources of light are just resolved as individual images when viewed by a naked eye.

The sources subtend an angle of 0.13 mrad at the naked eye. The eyeball may be assumed to be spherical with a diameter of 52 mm.

Calculate the maximum diameter of the receptor used.

I dunno if this is correct:

For images to be resolved two stimulated retinal cells must be separated by one stimulated retinal cell.

Therefore, diameter of three retinal cells:

tan (0.13/1000) x (52/1000) = 6.76 x 10^-6 m [can also use sin (0.13/1000) because of small angle approximation]

Max diameter of receptor (retinal cell) = (6.76 x 10^-6 ) / 3 = 2.25 x 10^-6 m (3 sf)

Only issue with this method is that it assumes there is a right-angled triangle, but I think that's why it said maximum diameter

Reply 1325

boyyo

Original post by marioman

Just a really rough guess - 54/75 for an A with Astrophysics option?

that seems about fair i guess. I think my worst case mark is probably 55/75, that would be 97/98 ums right?(assuming an A is 54)

Reply 1326

marioman

Original post by boyyo

that seems about fair i guess. I think my worst case mark is probably 55/75, that would be 97/98 ums right?(assuming an A is 54)

Should be. Not long to wait until the actual boundaries come out now.

Reply 1327

boyyo

Original post by marioman

Should be. Not long to wait until the actual boundaries come out now.

Yhh ikr :/ will it be out at midnight tonight, or later on wednseday?

Reply 1328

marioman

Original post by boyyo

Yhh ikr :/ will it be out at midnight tonight, or later on wednseday?

From approximately 09:30 tomorrow morning according to AQA on Twitter.

Reply 1329

boyyo

Original post by marioman

From approximately 09:30 tomorrow morning according to AQA on Twitter.

Thanks. Its gonna be so nerve racking looking at them

Reply 1330

philo-jitsu

Well unit 5 option D boundaries are really nice...the unit 4 are okay but not great but it was an easyish exam....the isa boundaries are nasty but thats to be expected and i really dont see how unit 2 ishigher than last year!!!!??? Im sure people who did unit 2 will attest to this

Reply 1331

marioman

Also, 41/55 for an A* in the EMPA? Seems really high compared to usual.

Reply 1332

tanyapotter

Original post by marioman

Also, 41/55 for an A* in the EMPA? Seems really high compared to usual.

I expected it to be that high tbh - task 1 was pretty difficult but task 2 was one of the easiest yet, I reckon.

Reply 1333

DesignPredator

Original post by tanyapotter

I expected it to be that high tbh - task 1 was pretty difficult but task 2 was one of the easiest yet, I reckon.

Task 2 was harrrrddd I was physically sweating after it, your gradient?

Reply 1334

tanyapotter

Original post by DesignPredator

Task 2 was harrrrddd I was physically sweating after it, your gradient?

i have a feeling it was -1.85? wbu?

Reply 1335

DesignPredator

Original post by tanyapotter

i have a feeling it was -1.85? wbu?

-1.99, fack

Reply 1336

tanyapotter

Original post by DesignPredator

-1.99, fack

i think anything between -1.8 and -2.2 should be correct :smile:

we'll see the mark scheme soon enough, though..

Reply 1337

DesignPredator

Original post by tanyapotter

i think anything between -1.8 and -2.2 should be correct :smile:

we'll see the mark scheme soon enough, though..

The EMPA ranges are always a *****

Reply 1338

rory58824

Anyone think the boundaries are unusually high or is it just me?

Reply 1339

marioman

Original post by rory58824

Anyone think the boundaries are unusually high or is it just me?

Not really, Unit 4 was always going to be quite high since it was more straightforward than most previous papers. I'm just happy that full UMS is at 65 and not 69 or something!