Answer:
Option (D)
Explanation:
Reflection is the phenomenon in which a ray of light strikes on a smooth and polished surface and then bounce back into the same medium at same angle.
There are two types of reflection.
1. Regular reflection or specular reflection
2. Irregular reflection or diffused reflection
When a parallel beam of light falls on a smooth and highly polished surface and after reflection the rays are also parallel to each other, it is called regular reflection.
When after parallel beam of light falls on a rough surface and after reflection the rays of light goes in random directions, it is called diffused reflection.
The rays reflected at 90 degree to - 90 degree in diffused refectory.
Answer:
Explanation:
Given
mass of core
Average specific heat 
And rate of increase of temperature =
Now
P=
Thus ![\frac{\mathrm{d}T}{\mathrm{d} t}=[tex]\frac{1.60\times 10^5\times 0.3349}{150\times 10^6}](https://tex.z-dn.net/?f=%5Cfrac%7B%5Cmathrm%7Bd%7DT%7D%7B%5Cmathrm%7Bd%7D%20t%7D%3D%5Btex%5D%5Cfrac%7B1.60%5Ctimes%2010%5E5%5Ctimes%200.3349%7D%7B150%5Ctimes%2010%5E6%7D)
A) We want to find the work function of the potassium. Apply this equation:
E = 1243/λ - Φ
E = energy of photoelectron, λ = incoming light wavelength, Φ = potassium work function
Given values:
E = 2.93eV, λ = 240nm
Plug in and solve for Φ:
2.93 = 1243/240 - Φ
Φ = 2.25eV
B) We want to find the threshold wavelength, i.e. find the wavelength such that the energy E of the photoelectrons is 0eV. Plug in E = 0eV and Φ = 2.25eV and solve for the threshold wavelength λ:
E = 1243/λ - Φ
0 = 1243/λ - Φ
0 = 1243/λ - 2.25
λ = 552nm
C) We want to find the frequency associated with the threshold wavelength. Apply this equation:
c = fλ
c = speed of light in a vacuum, f = frequency, λ = wavelength
Given values:
c = 3×10⁸m/s, λ = 5.52×10⁻⁷m
Plug in and solve for f:
3×10⁸ = f(5.52×10⁻⁷)
f = 5.43×10¹⁴Hz
