THE ELECTRIC FIELD E AT A POINT ASSOCIATED WITH A LIGHT WAVE IS E=100[SIN(3.14T INTO TEN POWER 15 )+SIN(6.28 TINTO TEN POWER 15 )]V/M .IF THIS LIGHT FALLS ON A METL OF WORK FUNCTION OF 2ev MAX. K.E. OF EMITTED ELECTRONS IS?

sai anth sastry Grade: 12

        THE ELECTRIC FIELD E AT A POINT ASSOCIATED WITH A LIGHT WAVE IS

E=100[SIN(3.14T INTO TEN POWER 15 )+SIN(6.28 TINTO TEN POWER 15 )]V/M .IF THIS LIGHT FALLS ON A METL OF WORK FUNCTION OF 2ev MAX. K.E. OF EMITTED ELECTRONS IS?

11 years ago

Answers : (1)

AskiitianExpert Shine

10 Points

							Hi
The electric field stores energy. The energy density of the electric field is given by

where
 is the permittivity of the medium in which the field exists
 is the electric field vector.
The total energy stored in the electric field in a given volume V is therefore

where
 $d V$  is the differential volume element
Energy associated with an electric field is 1/2ε₀E² . find the energy assosiated. 
Then , apply the formula for photoelectric effect, i.e energy given = work fn + max K.E . Convert the respective units into ev. 
Photoelectric effect
In effect quantitatively using Einstein's method, the following equivalent equations are used (valid for visible and ultraviolet radiation):
Energy of photon = Energy needed to remove an electron + Kinetic energy of the emitted electron
Algebraically:

where

     $h$  is Planck's constant,
     $f$  is the frequency of the incident photon,
     $φ = h f 0$  is the work function (sometimes denoted  $W$  instead), the minimum energy required to remove a delocalised electron from the surface of any given metal,
     is the maximum kinetic energy of ejected electrons,
     $f 0$  is the threshold frequency for the photoelectric effect to occur,
     $m$  is the rest mass of the ejected electron, and
     $v m$  is the speed of the ejected electron.