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NCERT Class XI Chemistry Structure of Atom Solutions

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Question : 12 of 67
Marks: +1, -0
Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate threshold frequency (u0u_0) and work function (W0W_0) of the metal.
Solution:  
Threshold frequency
(υ0)(\upsilon_0) = cλ\frac{c}{\lambda} = 3×1086800×10−10\frac{3 \times 10^8}{6800 \times 10^{-10}} = 4.41 × 1014s−110^{14} \mathrm{s}^{-1} [1 Å = 10−1010^{-10} m]
Work function (W0)(W_0) = hυ0h\upsilon_0 = 6.626 × 10−3410^{-34} × 4.41 × 101410^{14} = 2.92 × 10−19J10^{-19} \mathrm{J}
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