Wavelength of a photon radiation containing energy E is 4000 angstrom then wavelength of an other photon radiation containing energy 0.5 E will be-(1)2000 angstrom (2)8000 angstrom (3)4000 angstrom (4)6000 angstromExplain???

@ nitin 
the ques is very simple . 
this ques demands the relationship between wavelength and energy of the photon . 
so, acc to the photoelectric equation , we knows that 
E = H v ( v means frequency ) 
SO, further we can broken the frequency part into  v = c / lambda 
so, by substututing 
E= H C / lambda 
here H and C are constant , so, we can say . 
E = 1/ lambda , and here we got the inverse relationship 
so, as the energy will become half in 2^nd case the wavelength will become double . 
option 2 turns out to be the correct option 
HOPE IT CLEARS