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Question
In the following arrangement y=1.0 mm,d=0.24 mm and D=1.2 m. The work function of the material of the emitter is 2.2 eV. The stopping potential V needed to stop the photo current will be
In the following arrangement y=1.0 mm,d=0.24 mm and D=1.2 m. The work function of the material of the emitter is 2.2 eV. The stopping potential V needed to stop the photo current will be
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Solution
The correct option is A 0.9 V
From Young's Double Slit experiment fringe width is given by
2y=λDd⇒λ=2×1×10−3×0.24×10−31.2=4000 Angstrom
From photoelectric equation we can say that
hcλ−ϕ=eV0 .....(i)
where
ϕ=work functione=charge of electronV0=stopping potential
hcλ=12.434000×10−10×10−7eV=3.1 eV
Putting this in eq(i)
3.1−2.2=eV0⇒0.9 eV=eV0V0=0.9 V
From Young's Double Slit experiment fringe width is given by
2y=λDd⇒λ=2×1×10−3×0.24×10−31.2=4000 Angstrom
From photoelectric equation we can say that
hcλ−ϕ=eV0 .....(i)
where
ϕ=work functione=charge of electronV0=stopping potential
hcλ=12.434000×10−10×10−7eV=3.1 eV
Putting this in eq(i)
3.1−2.2=eV0⇒0.9 eV=eV0V0=0.9 V
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