Department of Pre-University Education, Karnataka course PUC Karnataka Science Class 12
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# Div » P When 40 Kv is Applied Across an X-ray Tube, X-ray is Obtained with a Maximum Frequency of 9.7 × 1018 Hz. Calculate the Value of Planck Constant from These Data. - Physics

ConceptElectromagnetic Spectrum

#### Question

When 40 kV is applied across an X-ray tube, X-ray is obtained with a maximum frequency of 9.7 × 1018 Hz. Calculate the value of Planck constant from these data.

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

#### Solution

Given:-
Potential applied to the X-ray tube, V = 40 kV
Frequency of the X-ray, v = 9.7 × 1018 Hz
Wavelength (lambda) is given by

lambda = (hc)/(eV)

Here,
h = Planck's constant
c = Speed of light

e = 1.6 xx 10^-19

therefore lambda = (hc)/(eV)

⇒ lambda/c = h/(eV)

⇒ 1/v = h/(eV)  ..................(∵ v = c/lambda)

⇒ h = (eV)/v

⇒ h = (40 xx 10^3)/(9.7 xx 10^18) xx e

⇒ h = 4.12 xx 10^-15  "eVs"

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Solution Div » P When 40 Kv is Applied Across an X-ray Tube, X-ray is Obtained with a Maximum Frequency of 9.7 × 1018 Hz. Calculate the Value of Planck Constant from These Data. Concept: Electromagnetic Spectrum.
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