# Multiple Choice (1 Viewer)

#### Fizzy_Cyst

##### Well-Known Member
tbh, I didnt really read that question, lol.

#### Fizzy_Cyst

##### Well-Known Member
I would still say D!

He used that experiment to measure the speed of the generated radio waves

#### hjed

##### Member
I would still say D!

He used that experiment to measure the speed of the generated radio waves
Now that you mention the speed I remember it was intended to be about radio waves

#### Randox

##### Member
These are my answers. What mark am I looking at?
1) b
2) d
3) b
4) a
5) d
6) d
7) a
8) d
9) b
10) a
11) b
12) a
13) b
14) c
15) a
16) d
17) b
18) c
19) c
20) a

#### Randox

##### Member
These are my answers. What mark am I looking at?
1) b
2) d
3) b
4) a
5) d
6) d
7) a
8) d
9) b
10) a
11) b
12) a
13) b
14) c
15) a
16) d
17) b
18) c
19) c
20) a
Bump

#### Randox

##### Member
How do we know his are all right? Isn't 3 b?

Oh lol

#### yasminee96

##### Active Member
1B
2D
3B <- using right hand rule this is what I got, I remember this experiment does rotate around the magnet
4A
5D
6C
7A
8D
9B
10C
11B
12D <- both a and d are correct, but a is not completely correct as it dosen't mention balanced forces.
13D
14A -< e=V/d so as d decreases, e increases
15B -< pretty sure this is wrong, could someone explain why though?
16D
17C -< missed the back emf thing, was too busy working out that it wasn't effect by the rotation
18C
19C
20B
Q12, (a) is most correct. Meissner effect doesn't have anything to do with crystal lattice structure or the balancing of any gravitational forces anyway i believe.

14 should be (b) small values of d create very large values of E, and large values of d create very small values of E (suggested by your explanation too)

15 is (a) (panda15 explained already)

+Q17 looks like about 4 wrong

#### kq888

##### New Member
magnetic field is pointing to the left, current is pointing down so RHP rule will give a force into the page which is clockwise

#### HowToNoob101

##### Member
1) b
2) d
3) a
4) a
5) d
6) c
7) a
8) d
9) b
10) c
11) b
12) a
13) d
14) b
15) a
16) d
17) b
18) c
19) c
20) a
I've got everything the same as you, but 13-C, and 20-B.

#### AnimeX

##### Member
a) can someone explain 7? the word insulator threw me off a...
b) how do you calculate the threshhold frequency for 20? I just picked d, I shouldve went with b cause I dont think theyll ask a question where both are right...
c) can someone also explain 17?

##### Member
Crap. I got 15/20.

#### Menomaths

##### Exaı̸̸̸̸̸̸̸̸lted Member
a) can someone explain 7? the word insulator threw me off a...
b) how do you calculate the threshhold frequency for 20? I just picked d, I shouldve went with b cause I dont think theyll ask a question where both are right...
c) can someone also explain 17?
20:
Wavelength = 450nm = 450x10-9m
c=fλ f= c/λ = 3x108/450x10-9 = 6.66...x1014
So obviously it can't eject an electron from metal Y.

#### Hezz96

##### Member
1B
2D
3B <- using right hand rule this is what I got, I remember this experiment does rotate around the magnet
4A
5D
6C
7A
8D
9B
10C
11B
12D <- both a and d are correct, but a is not completely correct as it dosen't mention balanced forces.
13D
14A -< e=V/d so as d decreases, e increases
15B -< pretty sure this is wrong, could someone explain why though?
16D
17C -< missed the back emf thing, was too busy working out that it wasn't effect by the rotation
18C
19C
20B
I agree that 3 should be b. Using the right hand rule the field lines are in the same direction (attracted) on the side closest to us and in oppisite directions (repelled) on the far side or the rod. Therefore it spins anticlockwise. I thing c was a distracter

#### anomalousdecay

14/20 and stuffed up the photocell. Band 5 is gonna be a mission now.

Feel so bad after getting a 19/20 in Chemistry.

#### Hezz96

##### Member
1B
2D
3B <- using right hand rule this is what I got, I remember this experiment does rotate around the magnet
4A
5D
6C
7A
8D
9B
10C
11B
12D <- both a and d are correct, but a is not completely correct as it dosen't mention balanced forces.
13D
14A -< e=V/d so as d decreases, e increases
15B -< pretty sure this is wrong, could someone explain why though?
16D
17C -< missed the back emf thing, was too busy working out that it wasn't effect by the rotation
18C
19C
20B
The answer to 15 is a. Force actually stays the same all the way around as the side of the coil is always 90 degrees to the field lines. We sometimes this that force gets less as the motor turns but is actually the turning force (torque) which gets less.

#### Fizzy_Cyst

##### Well-Known Member
I agree that 3 should be b. Using the right hand rule the field lines are in the same direction (attracted) on the side closest to us and in oppisite directions (repelled) on the far side or the rod. Therefore it spins anticlockwise. I thing c was a distracter
No.

3 is a.

Current down the wire, at the point where it is now, field lines to the left, RHP rule, force into page, viewed from above, would rotate clockwise

#### darkness70

##### Member
1) b
2) d
3) a
4) a
5) d
6) c
7) a
8) d
9) b
10) c
11) b
12) a
13) d
14) b
15) a
16) d
17) b
18) c
19) c
20) b

Tossing up between 17 b or d.. probably determines my 19/20 or 20/20