# The X-ray Coming from a Coolidge Tube Has a Cutoff Wavelength of 80 Pm. Find the Kinetic Energy of the Electrons Hitting the Target. - Physics

Sum

The X-ray coming from a Coolidge tube has a cutoff wavelength of 80 pm. Find the kinetic energy of the electrons hitting the target.

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

#### Solution

Given:-

Cutoff wavelength of the Coolidge tube, lambda = 80  "pm"

Energy of the electron hitting the target (E) is given by

E = (hc)/lambda

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

therefore E = (1242  "eV"-"nm")/(80 xx 10^-3)

⇒ E = (1242 xx 10^-9  "eV")/(80 xx 10^-12)

⇒ E = 15.525 xx 10^3  "eV" ≈ 15.5  "keV"

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