Physics 8.1.5-6: Nuclear Radius and Mass and Energy

26 flashcards · Physics · by TheoTyson

  1. Describe the closest approach of a scattered particle

    When an alpha particle is fired at a nucleus it will have kinetic energy related to the mass and velocity. When this energy is equal to the potential energy of the nucleus it will bounce back. This is the conservation of energy. Using the equation Ealpha=QgoldQalpha4πϵ0rE_\text{alpha} = \frac{Q_\text{gold}Q_\text{alpha}}{4\pi\epsilon_0r}Ealpha​=4πϵ0​rQgold​Qalpha​​ , an estimate for the maximum of the radius can be found.

  2. Describe electron diffraction to estimate the radius of the nucleus

    When an electron is fired at a high speed and passed through a thin material, it shows wave-particle duality and can be diffracted. Due to constructive and destructive interference, the diffraction pattern has a first minimum. Using the angle of the minimum and the de Broglie wavelength, sin⁡θ=0.61λr\sin\theta = \frac{0.61\lambda}{r}sinθ=r0.61λ​ estimates the radius.

  3. What is the graph for θ\thetaθ and light intensity\text{light intensity}light intensity for electron diffraction?

  4. What is an approximate value for the radius of the atom?

    50pm50\text{pm}50pm

  5. What is an approximate value for the radius of the nucleus?

    1fm1\text{fm}1fm

  6. What is the derivation of R=R0A13R = R_0A^{\frac{1}{3}}R=R0​A31​ ?

    Vnucleus=VnucleonV_{\text{nucleus}} = V_{\text{nucleon}}Vnucleus​=Vnucleon​ x AAA 43π(rnucleus)3=43π(rnucleon)3\frac{4}{3}\pi{(r_{\text{nucleus}})}^3 = \frac{4}{3}\pi{(r_{\text{nucleon}})}^334​π(rnucleus​)3=34​π(rnucleon​)3 x AAA (rnucleus)3=(rnucleon)3{(r_{\text{nucleus}})}^3 = {(r_{\text{nucleon}})}^3(rnucleus​)3=(rnucleon​)3 x AAA R3=R03R^3 = {R_0}^3R3=R0​3 x AAA R=R0R = R_0R=R0​ A13A^{\frac{1}{3}}A31​

  7. How can R=R0A13R = R_0A^{\frac{1}{3}}R=R0​A31​ be derived from electron diffraction?

    Plotting a graph of RRR against A13A^{\frac{1}{3}}A31​ produces a straight line with a yyy -intercept of R0R_0R0​ which is 1.05fm1.05\text{fm}1.05fm .

  8. How do densities of nuclei vary?

    They are all the same, 1.451.451.45 x 101710^{17}1017 kgm−3\text{kgm}^{-3}kgm−3 .

  9. What does a heavy density of a nucleus suggest?

    That most of the atom is empty space, and most of the mass is concentrated in the nucleus.

  10. What is nuclear fission?

    When large unstable nuclei randomly split into two smaller nuclei.

  11. What is spontaneous fission?

    If fission happens to a nucleus by itself.

  12. Why is energy released during nuclear fission?

    The new smaller nuclei have binding energy that is released for each nucleon.

  13. What is the relationship between larger nuclei and fission?

    The larger the nuclei, the more unstable it will be and the more likely it is to undergo spontaneous fission.

  14. What is nuclear fusion?

    When two light nuclei combine to create a larger nucleus.

  15. Why is energy released during nuclear fusion?

    The heavier nucleus has a much higher binding energy.

  16. Why does nuclear fusion require a lot of energy?

    The nuclei are positive and so there is an electrostatic force of repulsion that needs to be overcome before they can fused together.

  17. What is the mass defect?

    The mass of the constituent parts minus the mass of the nucleus.

  18. What has a greater mass, a nucleus or the constituent parts?

    The mass of the constituent parts.

  19. What happens to the mass defect?

    The mass defect is converted to energy and released.

  20. What is the binding energy?

    The energy needed to separate al of the nucleons in a nucleus and is equivalent to the mass defect.

  21. What equation links mass defect and binding energy?

    E=mc2E = mc^2E=mc2

  22. What is 1u1\text{u}1u in MeV\text{MeV}MeV ?

    1u1\text{u}1u = 931.5MeV931.5 \text{MeV}931.5MeV

  23. What is the most stable element in the average binding energy per nucleon curve?

    Iron - 56Fe^{56}\text{Fe}56Fe

  24. Where do fusion and fission take place in the average binding energy per nucleon curve?

    Fusion to the left of 56Fe^{56}\text{Fe}56Fe , and fission to the right of 56Fe^{56}\text{Fe}56Fe .

  25. What is an estimate for the energy released during fusion?

    Binding energy in final nucleus - binding energy in the starting nuclei.

  26. What is an estimate for the energy released during fission?

    Binding energy in the final nuclei - binding energy in the starting nucleus.