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Zorluk: OrtaX-rays: Production, Properties, and Applications

An X-ray tube operates at an accelerating potential difference of 25.0 kV25.0\text{ kV}. Calculate the maximum frequency of the emitted X-ray radiation in units of 1018 Hz10^{18}\text{ Hz}. (Take Planck's constant h=6.63×1034 Jsh = 6.63 \times 10^{-34}\text{ J}\cdot\text{s} and elementary charge e=1.60×1019 Ce = 1.60 \times 10^{-19}\text{ C}).

Cevap: 6.03 10^18 Hz

Cevap

The maximum frequency of the emitted X-rays is 6.03×1018 Hz6.03 \times 10^{18}\text{ Hz}, which gives a value of 6.036.03 in units of 1018 Hz10^{18}\text{ Hz}.
The maximum frequency of X-ray photons emitted occurs when an accelerating electron transfers all of its kinetic energy (eVe V) into a single photon (hfmaxh f_{\text{max}}). Substituting e=1.60×1019 Ce = 1.60 \times 10^{-19}\text{ C}, V=25,000 VV = 25,000\text{ V}, and h=6.63×1034 Jsh = 6.63 \times 10^{-34}\text{ J}\cdot\text{s} gives fmax=6.03×1018 Hzf_{\text{max}} = 6.03 \times 10^{18}\text{ Hz}, which equals 6.036.03 in the requested unit of 1018 Hz10^{18}\text{ Hz}.

Adım Adım Çözüm

1
Convert potential difference from kilovolts to volts
V=25.0 kV=25,000 VV = 25.0\text{ kV} = 25,000\text{ V}
Standard SI units are required for calculations.
2
Determine maximum kinetic energy of the incident electrons
Emax=eV=1.60×1019 C×25,000 V=4.00×1015 JE_{\text{max}} = e V = 1.60 \times 10^{-19}\text{ C} \times 25,000\text{ V} = 4.00 \times 10^{-15}\text{ J}
The maximum photon energy produced equals the full kinetic energy acquired by an accelerated electron.
3
Calculate maximum frequency fmaxf_{\text{max}} using Duane-Hunt relation
fmax=Emaxh=4.00×1015 J6.63×1034 Js6.03×1018 Hzf_{\text{max}} = \frac{E_{\text{max}}}{h} = \frac{4.00 \times 10^{-15}\text{ J}}{6.63 \times 10^{-34}\text{ J}\cdot\text{s}} \approx 6.03 \times 10^{18}\text{ Hz}
According to the Duane-Hunt law, eV=hfmaxe V = h f_{\text{max}}.

Anahtar Kavram

Duane-Hunt Law and Maximum X-ray Frequency
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