physics help

[ahmed t]

if there is a metal wire with no current passing thru it then
A)the electrons are not moving
B)the electrons are vibrating
C)the electrons are moving randomly
D)the electrons are moving in equal amounts in opposite direction

i said D because the net rate of flow of charge would be zero
reply ASAP
thanks

 

[ahmed t]

ANY ONE!!!!!!!!!!!!!!!!!!!!!!!!

 

[XPFMember]

Assalamoalaikum!!

Well i am not sure but i can just make a guess..it's A
do u know what's the correct answer..is it from pastpapers??

 

[larina]

it seems like chemistry rather than physics :shock:

as metal wire has metallic bonding which means that there is a lattice of positive ions in the sea of delocalised electrons.
so the electrons are always free to move whether current is passing or not.
so i think its C...btw whats the answer in the markscheme if its from the pastpaper?

 

[ahmed t]

it seems like chemistry rather than physics :shock:

as metal wire has metallic bonding which means that there is a lattice of positive ions in the sea of delocalised electrons.
so the electrons are always free to move whether current is passing or not.
so i think its C...btw whats the answer in the markscheme if its from the pastpaper?

yea i know,
so A and B are incorrect, couldnt find the anser any where
and no its not from pastpapers

 

[larina]

why will it be D?

 

[loly23]

I think it's A.
If there is no current it means that there is no movement of charge, neither +ve or -ve charges hence this means the electrons are not moving!
According to me..

 

[XPFMember]

that's what i think..but the problem is larina's reasoning doesnt seem to be wrong!

 

[ahmed t]

the correct ans is C
quoted from wikipedia
A solid conductive metal contains mobile, or free electrons, originating in the conduction electrons. These electrons are bound to the metal lattice but no longer to any individual atom. Even with no external electric field applied, these electrons move about randomly due to thermal energy but, on average, there is zero net current within the metal.

 

[ahmed t]

another question
if u have a closed tube of length "L" the fundamental frequency would be "F"
with an open tube what would u do to the length "L" to obtain same frequency "F"

 

[larina]

speed=lambda x frequency
S = L F
same= L x same
so we keep the length same to get the same frequency.

well, i know that this equation is applied for waves, but there's no other equation linking F and L.

 

[ahmed t]

they are stationary waves
not use speed=lamda x frequency
there are seperate equations

 

[Bimal]

I think its C.its because the delocalised electrons in a metallic lattice are moving randomly.

 

[hassam]

and this is wat 1st chapter of chemistry says......electrons are moving randomly (Heisenberg Uncertainty Principle).......
the things we learn abt current electricity....its like gross simplification....bt random nature is not limited by current...and i dont know wat causes this random nature.......Cshud be anser....and frequecy question....i dint get exactly...

 

[larina]

@ahmed yeah thats what im saying, bt there is no other equation which can link frequency and the length except this one.