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Author Topic: VCE Physics Question Thread!  (Read 603336 times)  Share 

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Bri MT

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Re: VCE Physics Question Thread!
« Reply #1845 on: September 19, 2017, 07:33:46 pm »
+3
so we did a prac where we dropped magnets through solenoids the other day,
and we got the graphs that look like one period of a positive sine graph.

What can we do with this graph? use emf = -N d(flux)/dt  to calculate what the change in flux was? is this the equation for average emf? and do we use the peak values for this?

is finding the area under the graph to calculate the strength of the magnets possible???


Yes, that is the equation for average emf.
It is possible to start square counting. If you know how to, you can find the area by integrating. If you don't, count squares. 

simrat99

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Re: VCE Physics Question Thread!
« Reply #1846 on: September 20, 2017, 07:15:11 pm »
+1
Hi,
Does an increase in intensity affect the Kinetic Energy of the photoelectrons in the Phototelectric effect?
Thanks  :)

BlinkieBill

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Re: VCE Physics Question Thread!
« Reply #1847 on: September 20, 2017, 07:32:50 pm »
+6
Does an increase in intensity affect the Kinetic Energy of the photoelectrons in the Phototelectric effect?
An increase in intensity does not affect the kinetic energy, it increases the no. of photoelectrons (current)
however, an increase in the frequency of light does increase the kinetic energy of the photoelectrons
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princessofpersia

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Re: VCE Physics Question Thread!
« Reply #1848 on: September 30, 2017, 05:49:58 pm »
+1
Guys,

did you learn about light dispersion in concave and convex lenses.
I'm asking b/c edrolo teaches it, but we never covered it in class.



Syndicate

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Re: VCE Physics Question Thread!
« Reply #1849 on: September 30, 2017, 05:55:02 pm »
+3
Guys,

did you learn about light dispersion in concave and convex lenses.
I'm asking b/c edrolo teaches it, but we never covered it in class.




It is part of unit 2, I doubt you'll have to know it for the exams (best to confirm with your teacher though).
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sweetiepi

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Re: VCE Physics Question Thread!
« Reply #1850 on: September 30, 2017, 05:56:44 pm »
+7
Guys,

did you learn about light dispersion in concave and convex lenses.
I'm asking b/c edrolo teaches it, but we never covered it in class.
Hey!

According to the VCAA study design this is what is assessable in regards to convex and concave lenses for unit 2:
"- describe image formation using pinhole cameras and convex and concave lenses
  ...
•distinguish between short-sightedness and long-sightedness, and explain their correction by concave and convex lenses, respectively"

I hope this helps :)
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Bri MT

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Re: VCE Physics Question Thread!
« Reply #1851 on: September 30, 2017, 08:06:13 pm »
+6
Guys,

did you learn about light dispersion in concave and convex lenses.
I'm asking b/c edrolo teaches it, but we never covered it in class.




From the study design (unit 4)  "•    investigate and explain theoretically and practically colour dispersion in prisms and lenses with reference to
refraction of the components of white light as they pass from one medium to another"

To be safe, I would understand what  direction of bending occurs, and the impact of changing colour on the degree of bending/diffraction.

princessofpersia

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Re: VCE Physics Question Thread!
« Reply #1852 on: October 01, 2017, 11:35:14 am »
+1
Thank everybody  ;D,

and just to be safe I think I'll learn the affect of bending and colour changing as miniturtle suggested.

TooLazy

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Re: VCE Physics Question Thread!
« Reply #1853 on: October 01, 2017, 03:07:41 pm »
+3
Do we have to know circuits.
Like calculating resistance across various components in series/parrallel.

I've noticed that much of what we did in unit 1/2 in that regard is absent in the unit 3/4 course. Is it safe to presume that we wont be asked any of those sorts of questions in the exam?
Future engineer

sweetiepi

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Re: VCE Physics Question Thread!
« Reply #1854 on: October 01, 2017, 03:19:09 pm »
+6
Do we have to know circuits.
Like calculating resistance across various components in series/parrallel.

I've noticed that much of what we did in unit 1/2 in that regard is absent in the unit 3/4 course. Is it safe to presume that we wont be asked any of those sorts of questions in the exam?
Hey!
I just skimmed through the VCAA study design, and I found no real mention of the circuitry outside of units 1 and 2. As I only skimmed through, I'd ask your teacher just to be 100% sure, however I believe it is highly unlikely to be assessed, given that I couldn't find much on it in the 3/4 design :)
« Last Edit: October 01, 2017, 03:24:12 pm by insanipi »
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kevinkyle28

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Re: VCE Physics Question Thread!
« Reply #1855 on: October 01, 2017, 05:58:00 pm »
+1
For the pre written notes for the physics exam, are you allowed to bring in 1 double sided a4 (so basically 2 pages) or are you allowed to bring in 2 double sided a4 (so basically 4 pages)

sweetiepi

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Re: VCE Physics Question Thread!
« Reply #1856 on: October 01, 2017, 06:02:11 pm »
+5
For the pre written notes for the physics exam, are you allowed to bring in 1 double sided a4 (so basically 2 pages) or are you allowed to bring in 2 double sided a4 (so basically 4 pages)
According to VCAA: "Pre-written notes  (one folded  A3 sheet or  two  A4 sheets  bound together  by  tape)". I'm pretty sure this is the same specifications that we had last year, therefore definitely 2 double-sided A4 pages are allowed :)
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Bri MT

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Re: VCE Physics Question Thread!
« Reply #1857 on: October 01, 2017, 07:11:45 pm »
+4
Do we have to know circuits.
Like calculating resistance across various components in series/parrallel.

I've noticed that much of what we did in unit 1/2 in that regard is absent in the unit 3/4 course. Is it safe to presume that we wont be asked any of those sorts of questions in the exam?

You may need to add up the resistance of wires when looking at the transmission of electrical energy across power lines. We haven't had to do any calculations involving circuits in series. You do need to be able to use formulas such as ohms law

Rowan1999

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Re: VCE Physics Question Thread!
« Reply #1858 on: October 01, 2017, 10:48:56 pm »
0
Hey,

Quick question regarding one of the special relativity questions from the 2015 VCAA exam (Question 5) (Answer is D)

Spacecraft S66 is travelling at high speed away from Earth carrying a highly accurate atomic clock. Another spacecraft, T50, is travelling in the opposite direction to S66, as shown in Figure 1.

An observer, E, on Earth emits a short radio pulse to spacecraft S66, which reflects it directly back towards the
observer. The time elapsed for E between sending and receiving the pulse is 20.0 ms.
Which one of the following is true?
A. According to E, spacecraft S66 was more than 3000 km away when the pulse reached it.
B. According to E, the pulse took longer to reach spacecraft S66 than it did to return from spacecraft S66 to E.
C. The 20.0 ms interval measured by E is not a proper time because the radio pulse travelled away and back.
D. According to spacecraft S66, the time interval between the signal being sent and being received back by E is
greater than 20.0 ms.

I'm able to discount option A, but I'm having a hard time understanding why options B and C are false. I understand that at such high speeds, time dilation will occur, but how is that the 20.0 ms time observed by E is proper time? Is this because E is in the same frame of reference, space?
Also, given that this is a radio pulse, would not all observers see this travelling at the speed of light, hence making the Lorentz factor 0 and thereby time dilation undefined?

Cheers

Syndicate

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Re: VCE Physics Question Thread!
« Reply #1859 on: October 02, 2017, 02:09:39 pm »
+5
Hey,

Quick question regarding one of the special relativity questions from the 2015 VCAA exam (Question 5) (Answer is D)

Spacecraft S66 is travelling at high speed away from Earth carrying a highly accurate atomic clock. Another spacecraft, T50, is travelling in the opposite direction to S66, as shown in Figure 1.

An observer, E, on Earth emits a short radio pulse to spacecraft S66, which reflects it directly back towards the
observer. The time elapsed for E between sending and receiving the pulse is 20.0 ms.
Which one of the following is true?
A. According to E, spacecraft S66 was more than 3000 km away when the pulse reached it.
B. According to E, the pulse took longer to reach spacecraft S66 than it did to return from spacecraft S66 to E.
C. The 20.0 ms interval measured by E is not a proper time because the radio pulse travelled away and back.
D. According to spacecraft S66, the time interval between the signal being sent and being received back by E is
greater than 20.0 ms.

I'm able to discount option A, but I'm having a hard time understanding why options B and C are false. I understand that at such high speeds, time dilation will occur, but how is that the 20.0 ms time observed by E is proper time? Is this because E is in the same frame of reference, space?
Also, given that this is a radio pulse, would not all observers see this travelling at the speed of light, hence making the Lorentz factor 0 and thereby time dilation undefined?

Cheers

- B is wrong, as the times to reach the Spacecraft, and travel back to E will be the same.

- C is wrong, as proper time is defined as the time measured between two events occurring in the same position in space. Therefore 20 ms is the proper time, as it occurred in E's frame (remember he is the one who emitted the pulse. He is part of the frame in which the radio pulse is in).

- according to Spacecraft S66, E is moving away from it, so the radio pulse will have to travel a greater distance in its perspective. Therefore, in this case the time has been dilated. So D is correct, as time measured will be grater for him.

As for the Lorenz factor, you are using it in a wrong sense. So we use the velocity of the spacecraft or E, depending on which one is defined at rest. The proper time is the time for the radio pulse to reach the spacecraft, and return to E in its frame of reference. However, we are testing for which observer sees the dilated time on their clock.
« Last Edit: October 02, 2017, 02:11:46 pm by Syndicate »
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