Section I - Multiple Choice (4 Viewers)

[cookeemonstah]

radial magnetic field ensures a direct relationship. If it wast radial, then torque would keep changing as it turns.

 

[nicholash747]

YES! Thanks for supporting me mate!

I had 7A too but wasn't sure.

 

[oh well]

I got D for 8..

I = 0.03/(0.05*0.2sin(30))
ignored sin 90

yep that's what I did , duncha get 3?

 

[nicholash747]

yep that's what I did , duncha get 3?

I get 6

 

[machine2035]

Does anyone agree with my reasoning behind choosing B for 8?

 

[nucgaek]

you find the length of wire and then use F=BILsin 30 to find the I

theta is the angle between the conductor and the flux lines, not the cross section of field lines so theta = 90

 

[cookeemonstah]

no. the angle was 90

 

[Zeroes]

Re: General Thoughts: Physics

and lol the meissner effect one didn't have any correct answers cos of poor wording hahaha

Omg this! I immediately crossed out the correct one when I saw "some" field lines or whatever it said, then picked the one about currents (B I think?) cause I didn't realise it said currents in magnets. :|

 

[machine2035]

no. the angle was 90

Winning... I knew going over trick questions from past papers would help.. There was 3 that I had seen in past ones that I got tricked on when practicing.. Pays off

 

[oh well]

no no , you find the length of the conductor using Sin Ratio i.e. l= 0.2 / sin30

then you sub it in F=BIlsin 30

how is the angle 90?

 

[cookeemonstah]

zzz. the wire is completely immersed in a magnetic field so its 90.

 

[nicholash747]

no no , you find the length of the conductor using Sin Ratio i.e. l= 0.2 / sin30

then you sub it in F=BIlsin 30

how is the angle 90?

Because the wire is PERPENDICULAR to the magnetic field.

 

[nmdsntfi]

sin30=0.2/l
l=0.2/sin30 = 0.4

0.03 = 0.05 x 0.4 x I x sin90
I = 0.03/(0.05 x 0.4)
= 1.5
?

 

[oh well]

Because the wire is PERPENDICULAR to the magnetic field.

but we take the angle the wire makes with the field far outtt guizeee

 

[himynameisbrody]

1. D
2.A
3. C
4. C
5. C
6. C
7. B
8. A
9. B
10. D
11. A
12. A
13. B
14. D
15. B
16. A
17. B
18. C
19. D
20. B

Not 100% sure on some

 

[cookeemonstah]

but we take the angle the wire makes with the field far outtt guizeee

Its a trick question, very common in past papers. ask ur teacher.

 

[nucgaek]

but we take the angle the wire makes with the field far outtt guizeee

Just to make it clear... you have to take this angle

 

[hscwav2012]

what about 2 - is it speed of light or krypton??

 

[v1]

20.A
calculate energy of photon. using around 10*10^-6m as wavelength. convert to ev get around 0.1eV which isnt enough energy to overcome the band gaps except for A

 

[hscwav2012]

Re: General Thoughts: Physics

what was 2 -was it the krypton or speed of light ?