Efficient power P=tN×λhc=200×0.25 tN=50×hcλ=6.6×10−34×3×10850×0.6×10−6=1.5×1020
A 200 W sodium street lamp emits yellow light of wavelength 0.6μm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
Held on 30 Apr 2012 · Verified 9 Jul 2026.
1.5×1020
6×1018
62×1020
3×1019
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De-Broglie wavelength of an electron orbiting in the $n=2$ state of hydrogen atom is close to (Given Bohr radius $=0.052 \mathrm{~nm}$ )
Which of the following options represent the variation of photoelectric current with property of light shown on the x -axis? 
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