Correct my physics homework (fun for 56Kers)

I'm just a bit unsure about some (alot) of the stuff in this physics paper. But I know a lot of people here at bit-tech know their way around a resistor (I should too...), so I figured you guys could correct it
I didn't even answer d) on page 3 (I tried, but got it all wrong).

Here's the link, four pages: http://www.home.no/mrbard/physics/

 

I was just wondering, how come your homework is English? I was half expecting a jumbled mess of incomprehensible Norwegian.

I'm afraid I can't help with the physics. Electronics was one of those things that my mind was never able to make sense of. I got about as far as Ohm's law and couldn't do anymore (I'm well aware that having this defeatist attitude probably never helped but I'm not a physicist so it doesn't matter now ).

 

Do you actually hand in your homework with bard written on it ?

 

I go to an IB school (International Baccalaureate) which means all my homework and classes are in English.
And yes, I do write Bard on my homework, as that is my name.

 

Come on, you can compress the images better than that - surely it's just black and white, no need for jpeg compression - use a 1bit format

Can't help you otherwise, no way am I downloading 600k pages on this connection

Rob.

 

I went to an IB highschool and got an IB diploma.

for the first question a.)ohmic means voltage and current increase linearly and the slope of that line should be 1/Resistance.

i dont wanna do the rest

 

I put up some 8 bit grayscale images in addition.

 

Well you still made me download pictures which were ten times bigger than needed, but I'll forgive you this once.

1 (a) - saying linearly is very important
(b) - don't like your use of the word 'current', why does more current mean more brightness? The answer is power, P=IV or I^2R
(e) - I'd guess you're supposed to picture ballistic transport, electrons picking up kinetic energy due to the potential difference and banging into atoms/electrons and losing this as heat.
(g) - not sure what they want here tbh
(i) what you say is basically right, but you could say it better - a volt meter has infinite resistance so when D breaks, C is in series with an infinite resistor, so there's no PD across C and the volt meter now reads the voltage across bulb B. So you've got A in series with B, identical bulbs, 7.5V will be dropped across each of them.

A3 (a) Yeah, picture it like a tube full of water, if you push on one end water comes out of the other instantaneously
(c) You've made no link to current and brightness again. Addind D makes the B-D combination effectively a resistor of half the value of a single bulb (1/(1/1+1/1) = 1/2) so you've now got R R/2 and R is series - so A and C have 12V dropped across them and B and D both 6V. Bulbs are rated at 3W for 10V so have 0.3A flowing through them at 10V, so are 30ohm resistors at this voltage. Assume this is constant and with the voltage across D it's easy to work out its power now.

MC4 - it'll decrease I=V/R, V is constant, if you double R, I halves.

MC8 - ohmic conductor resistance is constant R=V/I, R won't change, I will.

 

Ahhh, this is all easy stuff. I learned it my first semester as an electrical engineer. However, I'm very hung over right now and I probably should not go anywhere near these problems. If you need help I'll give it to you tomarrow... When I can see straight .

 

Hehe, sorry. Thanks alot for the help anyway. Next time I will make some beautiful 1-bit b/w images just for you