I need help with magnetic fields.
I think I mostly understand the theory. The problem is...well the problems. 😅

There are these questions which want you to find the force acting on one wire, when there are two other wires. Three wires in total, represented by dots or crosses, depending on direction of magnetic field. I understand how to find the magnitude through vector addition. But for the direction, the worked solutions generate a whole damn new triangle and I'm really heckin confused as to where they got it from. Like, how'd you get that angle? How'd you figure out that direction arrow? Why is the direction from the horizontal...and given in an angle????? What happened to up the page, down the page, into the page and out of the page???

Sorry for the rant, but my mind is teeming with questions.
Here's an example question:
https://imgur.com/a/Tl0aqWl

If someone could explain it in depth and address my questions above it will be very greatly appreciated, as I am really struggling to wrap my head around this concept. And my exam is in 27 days, and I'm behind on my Physics timetable. 😐

Thank you so much in advance,
-jinx_58

I’m doing VCE - which doesn’t have anything nearly this complex. But I’ll have a crack anyway…

Using the right hand grip rule, u find the direction of the magnetic fields. (Anticlockwise, clockwise)

Then u take the tangets from the circles, extend them along the lines to P.

The triangle is right angled: so
https://ibb.co/GvKK7QZ

I could be completely off the money here though… but was that the triangle u were after?

A and B are at right angles to each other???

Then use the forces to find the angle…

(The angle between A and the horizontal is 45° btw)

    jinx_58

    Actually, it might be!

    They just started with B - I started with A! (Imagine the green arrow starting from P, and the blue one starting from the top of the green arrow. )

    I assume if it were the exam, they would have to accept two angles? Because how do u know they wanted the acute one???

        God
        I see it now! That makes so much sense, Thank you so so so much!
        The question states it wants the direction of the force acting on P, and because its into the page? Is that why its the acute one?

        Mag fields are weird and thanks for helping, I really appreciate it!

        -jinx_58

        • God likes this.
          13 days later

          I need help with my IA3!!!!

          My stupid research assignment is due on Monday (final cuz procrastination duh) but anyways I'm hard-stuck on how to complete my 'Discussion' section, the one after your rationale and RQ.

          So my RQ is: "How does the sound exposure (volume and duration) to earphones affect the hearing health of Australian teenagers?"

          For the discussion section I'm trying to set it out in subheadings which are:

          • How hearing loss varies by age
          • How earphones actually cause hearing loss + what volume and durations are harmful.
          • Information to directly answer RQ.

          I need to know if this is good enough and also how to do the 2nd dot point. I don't know if I should discuss how earphones create sound waves, and the frequencies that are harmful. I'm trying to but the problem is that I can't find ANYTHING that answers this. If the sound wave stuff would actually be important is the main question.

          Please help! 😭 Btw I'm in yr10 so this is important so I can do physics next year. Also I'm the top of the class and don't want to lose that spot.

            DumbNerd
            Hey DumbNerd,

            Just FYI about some terminology, if you are in Grade 10 doing Unit 1&2 content now, your research investigation is called FA3 (rather than IA3) as this stands for "Formative Assessment 3". Assessments starting with "I" only refer to the ones in Grade 12 (Units 3&4) which count towards your ATAR. No stress tho 😀.

            As for your research investigation, I need to also know your claim to give a more accurate answer. I just want to quickly note that ensure you keep your 1st dot point within the confines of your RQ. Your RQ determines the scope of your investigation and you have specifically stated "the hearing health of Australian teenagers" so when you discuss the first point, don't talk about other age groups but rather investigate how listening to music now affects their hearing when they are older, if that makes sense.

            Considering this is a physics assignment, I can only assume that your claim and RQ focuses on sound waves (i.e. sound waves, frequency, wavelength, longitudinal waves etc.). So, I would highly recommend for you to discuss how earphones create sound waves and thus, what makes them harmful to the human ear. From your RQ, the bottom line is that you have to investigate how sound is good/bad for health. So, discuss how different frequencies (i.e. pitch of sound), different amplitudes (i.e. volume of sound) and different durations (i.e. time) affect the human ear (feel free to discuss how the tympanic membrane vibrates and transforms the vibrations to mechanical movements of the stapes, malleus and incus etc.). I would maybe alter your RQ very slightly and add "pitch" into the brackets as well so you can discuss the frequency of sound waves and make it more physics-y.

            The first point of contact should be your teacher so please ask them but my strong opinion on this would be that adding the "sound wave stuff" is very important to the RQ - its how you show off your physics knowledge.

            Anyways, hope that helped and feel free to be confused about what I said and ask questions 😆.

            • PP

                PhytoPlankton Thanks a lot for the advice! I'll try to find sources that actually give me helpful information (lol). By the way my claim is "Earphones have been linked to increased rates of hearing loss in Australia", very basic. Gonna work extra hard today. 🥲

                    9 days later

                    Howdy! Could someone please help me out with this question:

                    The period of revolution of the planet Saturn around the Sun is 30 times that of Earth. Determine how many times further Saturn is from the Sun than Earth.
                    A) 3.1
                    B) 5.5
                    C) 9.7
                    D) 30

                    The answer is C but I have not clue how they got there. The marking scheme stated the T2/r3 = 4pi2/GM formula.

                    -jinx_58

                      7 days later

                      DumbNerd

                      Ayyyyy congrats dude!! Was this for the research investigation?

                      -jinx_58

                        2 months later

                        Hii, am I still able to ask questions on this thread? If so, is it possible if I get feedback throughout my student experiment (and research question if possible) for physics (when we start working on it)? We are usually put in the same groups, but the group I has is way smarter than me, like they get 19 out of 20s, while I suffer with a 15 out of 20, but I'd really like to get better grades at least above an 18 this time?

                          Bibliii
                          Hey Bibliii,

                          You can certainly ask questions on any of the threads in the forum and definitely in this one (as long as its physics related 😆). If you mean feedback from your teacher, you should most likely be able to get feedback for certain sections of your assignment if you ask your teacher nicely. Our teachers didn't really; it was more like answering questions for us. However, I would imagine your teacher can't help you every step of the way with your assignment.
                          On here, though, feel free to post any questions, or sections of your assignment to receive feedback. Just like everyone else, I would be more than happy to assist you in providing feedback.

                          Hope that helps!

                          • PP

                              PhytoPlankton ahhh thank you so much. No I was just wondering if I could post and get help here, because my teacher constantly singles me out as I am not doing very well in physics (I average to below a C) and I'd really like to prove to myself and to her that I am better than that. She never gives me feedback, and when she does it's too complex or too simple and not enough. I try to work very hard, but it's never enough, so yeah any help from anyone except her is much appreciated!

                                  Bibliii
                                  All good and yeah, that does sound like a pain. You certainly can get feedback and help here whenever you need it. I have created a thread for urgent help for external exams but I will also create another one for urgent questions if you have a question the day before an assessment is due as well.

                                  There'll be people around to help.

                                  • PP

                                      Hiii,

                                      Could anyone please explain the right hand rule for electromagnetism. Also what does conventional current mean (is it the positive to negative or something like that is flippity flopped?)

                                      Thank youu

                                      • God replied to this.

                                        Bibliii

                                        Hi Bibliii,

                                        Conventional current is what we use to describe most circuits. It is the flow of charge (specifically positive charge).

                                        In chemistry, you view current as the flow of electrons. But because electrons are negatively charged, and old science people were stupid and thought they were positive, it is in the opposite direction.

                                        All u need to know is that conventional current flows from positive + to negative -!

                                        Where as the electrons flow from negative to positive.

                                        2) In terms of the ‘right hand rule’ there are two main ones.

                                        • Magnetic Force on a moving charged particle.
                                          Thumb in direction of current (direction the + charge is moving), fingers in direction of magnetic field, and ur palm shows the direction of the force.

                                        If it’s an electron, which is negative, u point ur thumb in the opposite direction to the electrons movement.

                                        • Magnetic Field from a wire.
                                          Thumb in direction of current. Curl fingers like a fist. Looking at it from the pinky end shows which way the magnetic field runs (clockwise/anticlockwise)

                                        There are two more, one for Lenz’s law: which is finding which direction the current must flow when a coil of wire is moved in a magnetic field. And one for finding the north/South Pole of a coil of wire (solenoid). But u can also use the magnetic field one instead, it just hurts ur head a bit more.

                                        Hope this helps,
                                        -G