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

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I got a tip from a guy on an A level physics facebook page:

before the exam even starts, ask for extra paper!! It'll help, The time you spend waiting for the invidulators to walk to the front and get it will be wasted. Do rough work on there for the MCQ's as there's never enough space

Reply 1061

TheLifelessRobot

Can someone explain how the answer is B?

phya4.jpg48.6KB

Reply 1062

thomas42

Original post by TheLifelessRobot

Can someone explain how the answer is B?

Mass = Rate x density = 0.2kg/s

Velocity = Rate/cross section = 0.28m/s

Momentum = mv = 0.056Ns

Reply 1063

TheLifelessRobot

Original post by thomas42

Mass = Rate x density = 0.2kg/s

Velocity = Rate/cross section = 0.28m/s

Momentum = mv = 0.056Ns

Thanks

Reply 1064

Applicant75235

Can someone plz help me with this question. Why is the answer A, and not B or even C?

Reply 1065

ManOfJustTin

Original post by koolgurl14

Can someone plz help me with this question. Why is the answer A, and not B or even C?

It can't be C cos the field is horizontal as well so no force is exerted?
And I guess it's not B cos if you use Fleming's Left Hand rule, the forces don't actually act as a couple as they point towards each other.
Not completely sure but that's my take on it :tongue:

Reply 1066

Applicant75235

Original post by ManOfJustTin

Yh I see what you mean but the forces will be point away from each other is that what you meant?

Reply 1067

ManOfJustTin

Original post by koolgurl14

Yh I see what you mean but the forces will be point away from each other is that what you meant?

I thought it was towards. I must be doing the stupid hand rule wrong then sorry 😅

Reply 1068

OldMathsAccount

Original post by ManOfJustTin

I thought it was towards. I must be doing the stupid hand rule wrong then sorry 😅

Nah the forces do point towards each other

Reply 1069

Applicant75235

Original post by cjlh

Nah the forces do point towards each other

What I am confused now are we using left hand rule ? is the current finger not up because we do it based on conventional current, god this is confusing why do i keep doing this wrong :frown:

Reply 1070

idk97

dw guys ill be lowering the grade boundaries for you all :smile:

im so screwed :smile:

Reply 1071

ManOfJustTin

Original post by koolgurl14

What I am confused now are we using left hand rule ? is the current finger not up because we do it based on conventional current, god this is confusing why do i keep doing this wrong :frown:

If we consider the closest wire, the current finger (middle) should point up with the first finger pointing in the field giving you motion inwards.

Reply 1072

SirRaza97

Original post by koolgurl14

What I am confused now are we using left hand rule ? is the current finger not up because we do it based on conventional current, god this is confusing why do i keep doing this wrong :frown:

Just remember this and you should be fine. Left hand rule for protons and current
Right hand rule for Generators and electrons.

Reply 1073

Applicant75235

Original post by SirRaza97

Just remember this and you should be fine. Left hand rule for protons and current
Right hand rule for Generators and electrons.

With current do you mean conventional current? if so in the questions is it a conventional current or electron direction that they are showing us?

Reply 1074

Shta15

The only positive thing about tomorrows exam is I can catch up on sleep.
Lets just say im unprepared for this.

Reply 1075

SirRaza97

Original post by koolgurl14

With current do you mean conventional current? if so in the questions is it a conventional current or electron direction that they are showing us?

Ive done all the papers and have always used LHR for current. Thats conventional current. I do not think itll be any different. Be wary though if they state otherwise in the question though

Reply 1076

Simple Harmonic

Original post by koolgurl14

With current do you mean conventional current? if so in the questions is it a conventional current or electron direction that they are showing us?

As far as I know, LHR works for both electron flow and conventional current flow, since - after all - conventional current flow is actually opposite to the direction of the electron flow.

Your left hand and right hand are non-superimposable mirror images, the rule works for both the proton and electron scenario.

Reply 1077

username1214456

When you can't sleep tho :/// lol
Gonna flop physics...

Good luck everyone 👍

Just a quick question about flux before we go in......... :-)

Good luck everyone, remember this is the fun part (sort of) you get to show off what youve learnt all year.....its game day!