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Ok thanks, I wondered how that happened. It's a complete a non-issue. You had to draw your solution on the graph provided, so irrespective of how x and y were labelled your solution just had to match the graph as given. It was pretty much just "joining the dots" anyway, and as with all...

I always love a controversial one, so I was interested to look at their rounding (to nearest minute) in Q27c. They did as I would have, and rounded 57.14 minutes to 57 minutes. The Matrix solutions however rounded up to the nearest minute, 58 minutes, so as to ensure the rounded solution meet or...

Thanks Queenroot. I thought that might have been the case. :)

After BOSTES gets the previous years exams uploaded, I usually like to take a look at the "Exam Thoughts" forums to get a feeling for how the students found the exams. For some reason the participation in the 2016 exam thoughts forums seems to be drastically reduced compared with previous...

Yes the question says that the magnet is moving up into the coil. But this is just to make clear which way the magnet is moving, not an invitation to choose whichever position you want for the magnet to be in when you analyse the field. There is no justification for analysing this problem with...

I don't have any written solutions, but if you want to ask about specific questions I'm sure someone will answer.

Maybe it would help if I explained it in steps. 1. Assume that the magnet starts out far away from the coil, so that initially there is no field inside the coil and no current flowing. 2. The magnet is then moved toward the coil as shown in the question. The field lines from the magnet enter...

Yes I was talking about the magnetic field lines INSIDE the coil, just as the question asked. The direction of the magnetic field inside the coil is downwards. So the correct answer is "A". I didn't sit the exam, I was just shown a copy of the paper today. TBH I would have been really torn...

Reread my post.There is absolutely no dispute about the direction of the INDUCED current, it's anticlockwise. I clearly stated that in the op. The question also asks for the direction of the magnetic field, and this is where the dispute lies.

I finally got a chance to look through the paper today. You know it wouldn't be a Physics HSC exam if there wasn't at least one controversial MC question. :rolleyes: I know that lots of people have posted their answers already and the consensus for MC7 is "B", but technically the correct answer...

It's just the line where the numbers got subbed in for the concentrations. It should read 0.1774^2 / (0.0129^2 x 0.0969) = 1952. Great, thanks for that info. :) I was trying to help my nephew prepare for his hsc and could see he had no idea what an equilibrium constant was. I wasn't sure...

You got everything spot on there Macca but just messed up the final numerical calc. :) I got Kc=1952 BTW. I've got an ulterior motive for butting in here. Can anyone tell if knowledge of equilibrium constants is currently part of the core (non elective) syllabus, or is it only in the Industrial...

Yes it's definitely related to back EMF. The key thing that they would have wanted here is to recognize the similarity of the DC motor and the DC generator (of course at the level expected here they are identical). So the one machine shifts seamlessly between being a motor and a generator, with...

No, but it's simulating the gravity of Earth, hence we use the same value. BTW. Sorry I haven't read all the replies here but from what I've read it looks like no one has put this answer into units of *rotational* speed (eg radians per second, revs per second, revs per minute etc). The correct...

You make a really good point. I hate the use of the term photocell to describe a light dependent resistor. The technically correct term for a solar cell is a “photovoltaic cell” and the best term for a light dependent resistor is (in my opinion) “a light dependent resistor” or a...

It says DC motor. DC simply means unidirectional current (or voltage), it makes no implication of whether either the voltage or current is constant.

Maybe they'll realize that they stuffed up (ambiguous question) and mark both b and d as correct. If they were just testing that students knew that a radial field implies that torque doesn't vary with angular position, then they might have expected a constant current assumption and hence answer...

Only if the motor is supplied from a constant voltage supply rather than a constant current. Something that the question did NOT specify!

Are you referring to Q17, I was just about to discuss that. That question is controversial in my opinion. The answer for 17 is b if motor is supplied by constant current, but is d if the motor is supplied by a constant voltage source. The question didn't specify whether the voltage was...

Good work RN, all correct there except for 20. Answer for 20 is b. Reason why 20 is b: The frequency of the light is c/lambda = 6.7E14, so *only* metal "X" is illuminated above the threshold for electron emission, so the number of emitted electrons increases only in metal "X". The number of...