Department of Pre-University Education, Karnataka course PUC Karnataka Science Class 12
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# The Stopping Potential in a Photoelectric Experiment is Linearly Related to the Inverse of the Wavelength (1/λ) of the Light Falling on the Cathode. the Potential Difference Applied Across an - Physics

ConceptElectromagnetic Spectrum

#### Question

The stopping potential in a photoelectric experiment is linearly related to the inverse of the wavelength (1/λ) of the light falling on the cathode. The potential difference applied across an X-ray tube is linearly related to the inverse of the cutoff wavelength (1/λ) of the X-ray emitted. Show that the slopes of the lines in the two cases are equal and find its value.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

#### Solution

V0 - Stopping Potential
K - Potential difference across X-ray tube
λ - Wavelength
λ - Cut difference Wavelength

eV_0 = hf - hf_0

lambda = (hc)/(eV)

eV_0 = (hc)/lambda

or  Vlambda = (hc)/e

or V_0lambda = (hc)/e

Here, the slopes are same.

i.e. V0λ = Vλ

(hc)/e = (6.63 xx 10^-34 xx 3 xx 10^8)/(1.6 xx 10^-19)

= 1.242 xx 10^-6  "Vm"

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Solution The Stopping Potential in a Photoelectric Experiment is Linearly Related to the Inverse of the Wavelength (1/λ) of the Light Falling on the Cathode. the Potential Difference Applied Across an Concept: Electromagnetic Spectrum.
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