Q2Q question (1 Viewer)

[Dumbarse]

do we have to know all the types of quarks and leptons, their symbols and their charges??

Also in this years Newington trial there was this question in quanta to quarks and i'm not sure how its done..

Q.An electric field is applied to a sample of hydrogen to stimulate the Balmer transition from n=2 to n=4

(i) Use the wavelength of this transistion (4.9 x 10^-7m) to calculate the corresponding energy difference between these quantum levels.

(ii) Use the energy of this transistion to calculate the corresponding voltage applied to stimulate the transition

?? help

 

[spice girl]

i) E = hf = hc/lambda
You should now have E in joules

ii) W = qV
V = W/q
W is energy from (i), q is charge of electron

 

[Dumbarse]

Originally posted by spice girl
i) E = hf = hc/lambda
You should now have E in joules

ii) W = qV
V = W/q
W is energy from (i), q is charge of electron

ohhh, is that it
i thought u had to do dome crazy thing with the energy levels,
thanx
how did u know, V= W/q i dont think we learnt that

also
the enrgy for the nth level is given by
E = -13.6 eV/ n^2

have u heard of that?, do we need this?> it was in my text book and ive never seen it before

 

[spice girl]

Yup, everything's good to know...
you would've needed to use the energy levels equation (Balmer's eqn), but since you've given me the wavelength, we skipped that step

 

[Dumbarse]

Originally posted by spice girl
Yup, everything's good to know...
you would've needed to use the energy levels equation (Balmer's eqn), but since you've given me the wavelength, we skipped that step

ohh, so we need to know

E = -13.6 eV/ n^2 ???

is there any other secret formulae for this sorta stuff that i dont know??, i only know the balmer eqn. and all the plank equations

v = w/q what topic is this equation from, ??

is it voltage = work over charge?

and in these examples work is the energy
so v = E/q

is this right?

 

[spice girl]

I think V = Ed

and W = qV (this is just the definition of electric potential, and we learnt this in our preliminary course) - one joule of work is done to move one coulomb of charge against one volt of potential difference.

and E = -13.6 eV/ n^2 only applies to the hydrogen atom, and is actually a re-phrasing of the Balmer's equation.

 

[ipicac]

out of interest:

F = Eq , W = Fd, V = Ed

therefore W=Eqd
and then W=qV

and:

W=Pt , P=IV, I=q/t

W/t=IV
W/t=q/t . V
W= qV