Answer:
λ = 470.66 nm
Explanation:
for bright fringe
D= distance between slit and screen
d= distance between the slits
for first order bright fringe m = 1,


for dark fringe,we have
Now to get the dark fringes at the same location we should have;
(706)D/d = (m + 1/2)λD/d
put m = 1
(1 + 1/2)λ = (706)
λ = 470.66 nm
He needs to improve his endurance time.
The marbles that are 'more energetic' fall out of the tray, in the same way particles have enough energy to escape and turn into a gas.
Explanation:
Given that,
Wavelength of the light, 
Work function of sodium, 
The kinetic energy of the ejected electron in terms of work function is given by :

The formula of kinetic energy is given by :

Hence, this is the required solution.
Which element is less reactive, an element whose atoms have seven valence electrons or an element whose atoms have eight valence electrons? Why?<span>an element with 8 valence electrons because it doesn't require any additional electrons to become stable</span>