Alevel生物学科必读书单！
最近，非常多同学学习Alevel生物。而生物作为一个探究人生奥秘的热门学科，却似乎因为专业性强，门槛高将同学们拒之于外。相信同学们都幻想过，忽然有一天学习生物变得有趣又令人着迷，再也不会枯燥了。这种想法...
AQA A Level Physics复习笔记8.3.6 Nuclear Radius Equation
Nuclear Radius Values The radius of some nuclei are shown in the table below: In general, nuclear radii are of the order 10–15 m or 1 fm The nuclear radius, R, varies with nucleon number, A ...
AQA A Level Physics复习笔记8.3.5 Closest Approach Estimate
Closest Approach Estimate The Coulomb equation can be used to give an estimate for the radius of a nucleus When the alpha particle reaches its closest approach (to the nucleus), all of its k...
AQA A Level Physics复习笔记8.3.4 Nuclear Radius
Estimating Nuclear Radius Closest Approach Method In the Rutherford scattering experiment, alpha particles are fired at a thin gold foil Some of the alpha particles are found to come straigh...
AQA A Level Physics复习笔记8.3.3 Nuclear Excited States
Nuclear Excited States In the same way that electrons can exist in excited states, nuclei can also exist in excited states After an unstable nucleus emits an alpha particle, beta particle or...
AQA A Level Physics复习笔记8.3.2 Decay Equations
Changes in N and Z by Radioactive Decay There are four reasons why a nucleus might become unstable, and these determine which decay mode will occur Too many neutrons Decays through beta-minu...
AQA A Level Physics复习笔记8.3.1 Nuclear Instability
Nuclear Stability Graph The most common elements in the universe all tend to have values of N and Z less than 20 (plus iron which has Z = 26, N = 30) Where: N = number of neutrons Z = number...
AQA A Level Physics复习笔记8.2.4 Applications of Radioactivity
Radioactive Dating The isotope carbon-14 is commonly used in radioactive dating It forms as a result of cosmic rays knocking out neutrons from nuclei, which then collide with nitrogen nuclei...
AQA A Level Physics复习笔记8.2.3 Half-Life
Half-Life Half-life is defined as: The time taken for the initial number of nuclei to halve for a particular isotope This means when a time equal to the half-life has passed, the activity of...
