Measurements on a certain isotope tell you that the decay rate decreases from decays/min to decays/min in days. What is the half-life of this isotope?
Ch 43: Nuclear Physics
42장, 문제 37
In a diagnostic x-ray procedure, photons are absorbed by tissue with a mass of kg. The x-ray wavelength is nm.
(a) What is the total energy absorbed by the tissue?
(b) What is the equivalent dose in rem?
검증된 단계별 안내1
Step 1: Calculate the energy of a single photon using the formula \( E = \frac{hc}{\lambda} \), where \( h \) is Planck's constant (\( 6.626 \times 10^{-34} \ \text{J·s} \)), \( c \) is the speed of light (\( 3.00 \times 10^8 \ \text{m/s} \)), and \( \lambda \) is the wavelength of the x-ray (\( 0.0200 \ \text{nm} = 0.0200 \times 10^{-9} \ \text{m} \)). Substitute the values to find the energy of one photon.
Step 2: Multiply the energy of a single photon by the total number of photons absorbed (\( 5.00 \times 10^{10} \)) to calculate the total energy absorbed by the tissue. Use the formula \( E_{\text{total}} = E_{\text{photon}} \times N \), where \( N \) is the number of photons.
Step 3: To calculate the equivalent dose in rem, first determine the absorbed dose in grays (Gy). Use the formula \( D = \frac{E_{\text{total}}}{m} \), where \( E_{\text{total}} \) is the total energy absorbed (in joules) and \( m \) is the mass of the tissue (\( 0.600 \ \text{kg} \)). This gives the absorbed dose in joules per kilogram, which is equivalent to grays (1 Gy = 1 J/kg).
Step 4: Convert the absorbed dose in grays to the equivalent dose in sieverts (Sv) by multiplying by the radiation weighting factor (\( W_R \)). For x-rays, \( W_R = 1 \), so the equivalent dose in sieverts is the same as the absorbed dose in grays.
Step 5: Convert the equivalent dose from sieverts to rem by using the conversion factor \( 1 \ \text{Sv} = 100 \ \text{rem} \). Multiply the equivalent dose in sieverts by 100 to find the equivalent dose in rem.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념
질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.
Photon Energy
The energy of a photon is determined by its wavelength and can be calculated using the formula E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. In this context, the x-ray wavelength of 0.0200 nm is crucial for determining the energy of each photon absorbed by the tissue.
추천 영상:
가이드 코스
Intro to Energy & Types of Energy
Total Energy Absorbed
The total energy absorbed by the tissue can be found by multiplying the energy of a single photon by the total number of photons absorbed. This is expressed mathematically as Total Energy = Number of Photons × Energy per Photon. This calculation is essential for understanding the impact of the x-ray exposure on the tissue.
추천 영상:
가이드 코스
Total Internal Energy
Equivalent Dose
Equivalent dose is a measure of the biological effect of radiation on human tissue, expressed in rem or sieverts. It accounts for the type of radiation and its impact on different tissues. To calculate the equivalent dose, the absorbed dose (in gray) is multiplied by a quality factor that reflects the relative biological effectiveness of the radiation type, which is important for assessing health risks.
추천 영상:
가이드 코스
Find Equivalent Capacitance #1
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