NEET Questions Solved


The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength λ for sodium is 5460 Å, the value of λ for tungsten is

(a) 5893 Å                   (b) 10683 Å
(c) 2791 Å                   (d) 528 Å

(c) Since 

W0=hcλ0;  W0TW0Na=λNaλT orλT=λNa×W0NaW0T=5460×2.34.5=2791 Å 

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