Answer: a) 274.34 nm; b) 1.74 eV c) 1.74 V
Explanation: In order to solve this problem we have to consider the energy balance for the photoelectric effect on tungsten:
h*ν = Ek+W ; where h is the Planck constant, ek the kinetic energy of electrons and W the work funcion of the metal catode.
In order to calculate the cutoff wavelength we have to consider that Ek=0
in this case h*ν=W
(h*c)/λ=4.52 eV
λ= (h*c)/4.52 eV
λ= (1240 eV*nm)/(4.52 eV)=274.34 nm
From this h*ν = Ek+W; we can calculate the kinetic energy for a radiation wavelength of 198 nm
then we have
(h*c)/(λ)-W= Ek
Ek=(1240 eV*nm)/(198 nm)-4.52 eV=1.74 eV
Finally, if we want to stop these electrons we have to applied a stop potental equal to 1.74 V . At this potential the photo-current drop to zero. This potential is lower to the catode, so this acts to slow down the ejected electrons from the catode.
The length of the wire is 36 m.
<u>Explanation:</u>
Given, Diameter of sphere = 6 cm
We know that, radius can be found by taking the half in the diameter value. So,
Similarly,
We know the below formulas,
When equating both the equations, we can find length of wire as below, where 
The 
value gets cancelled as common on both sides, we get
The 
value gets cancelled as common on both sides, we get
If the separation between the charges is increased then the magnitude of the force will increase in fact how the distance is being used in that formula.
By absorbing solar radiation and releasing heat needed to drive the atmospheric circulation
