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AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread]

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spent every bloody holiday in the library, revised for hours, and except 6 marker this was **** for me. Even worse, apparently im the only person who found it hard, so high boundaries. a D if i'm lucky. I'll just take a gap year, then try get into an apprenticeship. AAB required for surry, physics won't be more than a C after this.

Reply 1121

duncant

Original post by Rahul.G

No it was not that. You had to use ln0.2 not ln0.8

what was your answer?

Reply 1122

Ghettobadger

Original post by Rahul.G

No it was not that. You had to use ln0.2 not ln0.8

**** , i think you might be right there lol

Reply 1123

Examguy123

What did people get for the extra energy stored in the capacitor for question 1 section B

Reply 1124

RUNSran

Original post by duncant

got this but I got RC=28s? 45/-ln(0.2)

yeah i got same. I think people missed the 'decrease BY 80% '

Reply 1125

aelahi23

Original post by Rahul.G

No it was not that. You had to use ln0.2 not ln0.8

your right, how many marks was it?

Reply 1126

Beautywithabrain

Original post by Cadherin

I got 200s for time constant?

That was ok - some easy parts and some harder parts. I suspect grade boundaries will be normalish (62/75ish for 120 UMS).

I think I might have got that

Reply 1127

Beautywithabrain

Original post by RUNSran

yeah i got same. I think people missed the 'decrease BY 80% '

Oh sh*t! Praying for low grade boundaries now

Reply 1128

perpetua

Boundary predictions? CAP?

Reply 1129

Rid123

Original post by duncant

got this but I got RC=28s? 45/-ln(0.2)

Ahh no you are right...i forgot to ln...silly me :frown:

Reply 1130

justalawyer1998

Original post by Beautywithabrain

I think I might have got that

27.96 for time constant

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Reply 1131

Datta10

Original post by duncant

got this but I got RC=28s? 45/-ln(0.2)

I got 28s too for the time constant, then around 59000 ohms I think for resistance

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Reply 1132

crashMATHS

I worked out the energy of the capacitor by the area under the graph - is this valid?

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Reply 1133

Barbecuetime123

Original post by Beautywithabrain

I think I might have got that

It will be that for the A*, 120 will be a bit higher I reckon

Reply 1134

duncant

what did people say for the effect when that guy recorded only half of T? was it (1/4)g?

Reply 1135

Cadherin

Original post by Rahul.G

No it was not that. You had to use ln0.2 not ln0.8

I got 200s (2sf) - actually, I think it's right.

The question asked for a decrease TO 80% of its original value. (I'm almost certain).

Thus e^(t/RC) = ln(1.25)=t/RC

Reply 1136

rich1334

Original post by Cadherin

I got 200s (2sf) - actually, I think it's right.

The question asked for a decrease TO 80% of its original value. (I'm almost certain).

Thus e^(t/RC) = ln(1.25)=t/RC

The question definitely specified decreased by 80%, standard AQA trick

Reply 1137

Cadherin

Original post by perpetua

Boundary predictions? CAP?

62 is my guess for cap - there were some easier and some harder parts, so I would imagine it will be 4 marks higher than last year but 5 or so lower than June 13.

Plus I would imagine the facility of the multiple choice is a lot lower than usual (maybe 60% rather than 67%).