CONFIRMED mc answers! (2 Viewers)

[pdoueihi]

1C
2C
3B
4A
5C
6A
7C
8B
9B
10A
11D
12B
13A
14D
15D (according to my answer, my teachers answer and JRAHS teachers answers, however some STILL argue B)

im pretty sure these are right... any queries ask. i went through them with my teacher. best of luck.

edited: 4 is A coz my teacher got confused
also: comment on 15 with reasoning

 

[dolbinau]

4 is not C, time was not independent variable.

 

[independantz]

15- B
11-A

Are the only differences between mine and those.

15- i don't think it can be D as it's a p-type semiconductor thus the primary flow is holes which occur in the valence band

11 not quite sure on this one but i believe you have to take the component that moves at right angles to the magnetic field, that is how i did it- but im not sure on this.

 

[pdoueihi]

actually yeh it is A for 4

 

[dolbinau]

Dependent variable is being measured (Time).

11 is definitely D IMO.

 

[pdoueihi]

15- B
11-A

Are the only differences between mine and those.

15- i don't think it can be D as it's a p-type semiconductor thus the primary flow is holes which occur in the valence band

11 not quite sure on this one but i believe you have to take the component that moves at right angles to the magnetic field, that is how i did it- but im not sure on this.

for 11, it is already perpendicular visualise it into the page and moving on an angle.
for 15, im pretty sure D coz electrons flow from negative to positive either way, ie the smaller line in the battery to the bigger line around.

 

[Pwnage101]

1C
2C
3B
4C
5C (or arguably B)
6A
7C
8B
9B
10A
11D
12B
13A
14D
15D

im 100% sure these are right... any queries ask. i went through them with my teacher. best of luck.

ur teachers credibility goes out the door after q4

 

[Kearnzo]

4 is a, as height was measured and the time to fall taken.

Thus time is dependent on height.

Also 15 is B as holes are in the valence band and are the primary source of conduction in p-type semiconductors.

Teachers arn't infallible.

 

[Tellytubby]

Q4 is A not C.

The dependent variable is the one that depends on the other variable. In this case, the time it takes for the ball to reach the ground DEPENDS on the height it's dropped from. The height is being controlled, often time is plotted on the x axis but not in this case, which is probably what caused confusion.

 

[pdoueihi]

ok 4 is A! thats good we know now any others?

 

[pdoueihi]

4 is a, as height was measured and the time to fall taken.

Thus time is dependent on height.

Also 15 is B as holes are in the valence band and are the primary source of conduction in p-type semiconductors.

Teachers arn't infallible.

i think that 15 might be D coz the conduction band is the one which allows electrons to flow, like conductivity is determined by the ability of an electron to reach the condunction band from the valence band

 

[Daniel-08]

nope, 4 is def. A. The independent variable is the one that is being changed, the dependent variable is the one theat is measured. So height (the variable being changed) must be on the horizontal axis, meaning it cannot possibly be C

and for q 11, it is a trick q, the electron is actually moving perpidicular to the magentic field. All u hav 2 do is equate centripedal force and magnetic force, giving r= mv/qB. the answer is D

 

[cookiemonsterz]

1.c
2.c
3.b
4.a (know vairable, H, on x axis, unkown on y axis)
5.c (round up the answer from 0.625, even if it is going way the interval would be the same)
6.a
7.c
8.b
9.b
10.a
11.d
12.b
13.a
14.d
15.b or d (i put b but not 100% on either)

 

[snowconesyum]

Except if you remember those diagram/graph things showing the level of holes vs extra electrons and where they're situated in band theory, p-doping (which this was) means that electrons move out of the valence band, into the holes, thus carrying the charge - so i reckon it's B

 

[Kearnzo]

There are two sources of conduction in semiconductors, holes and electrons.

Semiconductors normally have a full valence band, but when a potential difference is applied they jump up, into the conduction band. Leaving behind as many holes as there are electrons that jump up.

Both holes and electrons cause conductivity equally in intrinsic (pure) semiconductors.

However if Boron is added, more holes are created as it only has 3 valence electrons compared to silicons 4.

Thus there are more holes, and as the question asked for the "main way in which conduction occurs" it is holes.

Look, i wrote so much i must be right!

 

[pdoueihi]

i am not 100% sure bout 15 nemore but ill leave it as a possibility

 

[pdoueihi]

There are two sources of conduction in semiconductors, holes and electrons.

Semiconductors normally have a full valence band, but when a potential difference is applied they jump up, into the conduction band. Leaving behind as many holes as there are electrons that jump up.

Both holes and electrons cause conductivity equally in intrinsic (pure) semiconductors.

However if Boron is added, more holes are created as it only has 3 valence electrons compared to silicons 4.

Thus there are more holes, and as the question asked for the "main way in which conduction occurs" it is holes.

Look, i wrote so much i must be right!

lol maybe the electrons move in the conduction band then fall back to the valence band. im not sure

 

[Kearnzo]

lol maybe the electrons move in the conduction band then fall back to the valence band. im not sure

Only when a potential difference stops being applied. Tricky question that one, I forget which way the current flowed, lucky another part of the paper told me .

 

[pdoueihi]

Only when a potential difference stops being applied. Tricky question that one, I forget which way the current flowed, lucky another part of the paper told me .

u might be right, but most ppl in my school put 15d (ie 4 out of the top 5)

 

[poisonives]

Question 12 is definitely a) Cathode rays can turn a paddle wheel.
And i'm question 15 is b) since conduction only occurs in the valence band in silicon doped with boron - P-TYPE doping

edit. alright so its no a) my bad