Multi choice Q15 (1 Viewer)

[timmiitippii]

Ahh, but I think that is the direction of conventional current. If it says which way conduction occurs, like the question said, it's from positive to negative.

But the time interval measured (0.5s), I assume, would have already included the extra time for the signal to reach earth.

no.. it said which way conduction occurs "in the doped silicon block". Not through the wire which for conventional current is the normal pos to neg. But in the silicon doped with boron, conduction happens differently im pretty sure

 

[old.skool.kid]

i think i put conduction band electrons go to the left, iirc

Same!

 

[Pwnage101]

i got B as the VALENCE BAND electrons move into the conduction band in order to conduct

same - its a p-type-- right?

thus, the conduction is by holes

holes are in teh VALENCE band, and not the OCNDUCTION band as they are the missing electron in the bond

thus to conduct, a neighbouring electron moves into its place - that neighbouring electron is ALSO in the valence band

thus i chose B

(could be wrong, though i hope not

..)

 

[Pwnage101]

I disagree. Fairly sure it is c.

QFT

 

[dolbinau]

holes are in teh VALENCE band, and not the OCNDUCTION band as they are the missing electron in the bond

thus to conduct, a neighbouring electron moves into its place - that neighbouring electron is ALSO in the valence band

thus i chose B

I thought the opposite, Holes are in the valence band so electrons move from conduction band to fill holes.

 

[cookiemonsterz]

lol lets get this straight. A and C are wrong for sure, we are tossing up between B and D as it is clear that they move left not right

 

[proringz]

lol lets get this straight. A and C are wrong for sure, we are tossing up between B and D as it is clear that they move left not right

Does anyone have a proper explanation for this? Why it moves left?

 

[dolbinau]

Does anyone have a proper explanation for this? Why it moves left?

Electrons move towards positive terminal..

 

[JamesTockuss]

I disagree. Fairly sure it is c.

It would be (c) if it were standing still and emitting the pulse. it's kind of like the red shift of the universe expanding if that helps

 

[adosh]

If you used the time dialation formula for 5 you got (c), but since the ship is moving away at a constant speed it's gunna take extra time for the signal to get to earth - so the answer had to be (d)

taht does sound correct ,,,but the thing is a radio wave travels the speed of light so it would reach the earth really fast so looking at c 0.63 adn d 0.78 the difference is 0.15. i think light woudl travle really fast sot hat if anything the time it woudl take tog et to earth woudl be small eg 0.0000000001 sec.. so maybe it is 0.63...

 

[proringz]

Electrons move towards positive terminal..

I'm not sure that's the right explanation. It's because the 'holes' flow in the same direction as conventional current i.e to the right. Electrons flow in the opposite direction to conventional current i.e left.

 

[Aaron.Judd]

i still think its D.

 

[dolbinau]

I'm not sure that's the right explanation. It's because the 'holes' flow in the same direction as conventional current i.e to the right. Electrons flow in the opposite direction to conventional current i.e left.

Isn't that the same thing? lol. Flow of electrons opposite to conventional current (Negative+Positive)=Left.

 

[samwell]

I put electrons in condution band moves towards the positive terminal. The holes in the superconductor enable movement of electrons in the condution band. I really dont think they move in the valency cause there is always an energy gap and doping just increases electons in the conduction band.

the time dilation one i got 0.63.

 

[timmiitippii]

I put electrons in condution band moves towards the positive terminal. The holes in the superconductor enable movement of electrons in the condution band. I really dont think they move in the valency cause there is always an energy gap and doping just increases electons in the conduction band.

the time dilation one i got 0.63.

*semiconductor

*doping with boron which only has 3 valence electrons cause overall for the silicon, which has 4 valence electrons, to be missing 1 electron for every million or so silicon atoms. So it doesn't increase electrons in the conduction band.
Holes conducts in the semiconductor from left to right in the valence band and its obvious that when a hole moves right, relatively its an electron moving left, so when they ask which conduction occurs "in the doped silicon block" with all choices referring to electrons*, its valence band electrons move to the left .. i.e B

 

[JamesTockuss]

taht does sound correct ,,,but the thing is a radio wave travels the speed of light so it would reach the earth really fast so looking at c 0.63 adn d 0.78 the difference is 0.15. i think light woudl travle really fast sot hat if anything the time it woudl take tog et to earth woudl be small eg 0.0000000001 sec.. so maybe it is 0.63...

But because the speed was so large, the distance it travels in one such is significant enough to make it (d) I think

 

[karnage]

d

 

[Pwnage101]

If you used the time dialation formula for 5 you got (c), but since the ship is moving away at a constant speed it's gunna take extra time for the signal to get to earth - so the answer had to be (d)

thats made me start thinking, yeh it is a confusing Q

but after thinkin about it - i rekonits (d)

Damn!!!! got it wrong

 

[dolbinau]

But because the speed was so large, the distance it travels in one such is significant enough to make it (d) I think

Where is the maths, though :-/

 

[samwell]

*semiconductor

*doping with boron which only has 3 valence electrons cause overall for the silicon, which has 4 valence electrons, to be missing 1 electron for every million or so silicon atoms. So it doesn't increase electrons in the conduction band.
Holes conducts in the semiconductor from left to right in the valence band and its obvious that when a hole moves right, relatively its an electron moving left, so when they ask which conduction occurs "in the doped silicon block" with all choices referring to electrons*, its valence band electrons move to the left .. i.e B

Ua answer is pretty accurate i have only one question though where is the acceptor band relative to the conduction and valence band?

[tnks i meant semiconductor.]