📚 Year 10 SQA Physics: Core Knowledge Organiser | SQA 物理 Year 10 核心知识点梳理
This guide brings together the essential facts and relationships that Year 10 learners in Scotland need for the SQA National 5 Physics course. Use it for quick revision of motion, forces, energy, electricity, waves, radiation and space, making sure you can link the key ideas with confidence.
本指南汇总了苏格兰 Year 10（对应 National 5）物理课程的核心知识点。它将帮助你快速回顾运动、力、能量、电学、波、辐射和宇宙等内容，牢固掌握这些关键概念之间的联系。
1. Scalars, Vectors and Motion | 标量、向量与运动
A scalar quantity has magnitude only; examples are distance, speed, time, mass and energy. A vector quantity has both magnitude and direction, such as displacement, velocity, acceleration and force.
标量只有大小，如距离、速率、时间、质量和能量。向量既有大小又有方向，如位移、速度、加速度和力。
Distance tells you how much ground an object has covered regardless of direction, so it is a scalar. Displacement is the straight‑line change of position in a particular direction, making it a vector.
距离表示物体经过的路径长度，不考虑方向，是标量。位移则是物体在指定方向上的直线位置变化，是向量。
When an object moves along a straight line without reversing, the magnitude of its displacement equals the distance travelled. In any other case the two values differ.
当物体沿直线运动且不反向时，位移的大小等于距离；其他情况下两者不相等。
2. Speed and Acceleration | 速度和加速度
Average speed is the total distance divided by the total time taken. Instantaneous speed is the speed at a specific instant.
平均速率等于总距离除以总时间。瞬时速率是物体在某一瞬间的速率。
v = d / t
Acceleration measures how quickly velocity changes. It is a vector: a positive value means speeding up in the chosen direction; a negative value means slowing down.
加速度描述速度变化的快慢，是向量。取正方向后，正加速度表示加速，负加速度表示减速。
a = (v - u) / t
On a velocity–time graph, the slope (gradient) gives the acceleration, and the area between the line and the time axis gives the displacement travelled.
在速度－时间图上，斜率表示加速度，图线与时间轴之间的面积表示位移。
3. Newton's Laws | 牛顿定律
Newton’s First Law states that an object remains at rest or moves with constant velocity unless an unbalanced force acts on it. This is the idea of inertia.
牛顿第一定律指出，除非受到不平衡力的作用，物体将保持静止或匀速直线运动状态，这就是惯性。
Newton’s Second Law links the unbalanced force, mass and acceleration: when an unbalanced force acts on an object, it accelerates in the direction of the force.
牛顿第二定律联系了不平衡力、质量和加速度：物体受到不平衡力时，会沿力的方向加速。
F = m a
Newton’s Third Law says that for every action force there is an equal and opposite reaction force. The two forces act on different objects.
牛顿第三定律指出，每一个作用力都有一个大小相等、方向相反的反作用力，这两个力作用在不同的物体上。
4. Energy and Power | 能量与功率
through a distance. If the force is parallel to the displacement, work = force × distance.
力使物体沿力的方向移动一段距离时做功。若力与位移平行，功等于力乘以距离。
W = F d
Gravitational potential energy is stored because of an object’s height. Kinetic energy depends on mass and speed.
重力势能是由于物体的高度而储存的能量。动能则取决于质量和速率。
Eₚ = m g h
Eₖ = ½ m v²
In a closed system, total energy is conserved; it can only be transformed from one type to another. Power is the rate at which energy is transferred or work is done.
在封闭系统中，总能量守恒，只能从一种形式转化为另一种形式。功率是能量转移或做功的速率。
P = E / t
5. Electric Circuits and Ohm's Law | 电路与欧姆定律
Electric current is the flow of charge. In a metal, it is carried by negatively charged electrons. Current is measured in amperes (A).
电流是电荷的流动。在金属中，电流由带负电的电子形成。电流的单位是安培（A）。
Voltage (potential difference) is the energy transferred per unit charge. Resistance measures how much a component opposes the flow of current.
电压（电势差）是单位电荷转移的能量。电阻衡量元件对电流阻碍作用的大小。
For many conductors at constant temperature, the current is directly proportional to the voltage. This is Ohm's Law.
对于在恒定温度下的许多导体，电流与电压成正比，这就是欧姆定律。
V = I R
An ohmic conductor gives a straight‑line graph of current against voltage passing through the origin. In a filament lamp the temperature rises, resistance increases and the graph curves.
欧姆导体的电流－电压图是一条通过原点的直线。白炽灯中温度升高，电阻变大，图线就会弯曲。
6. Series and Parallel Circuits | 串联和并联电路
| Property | 性质 | Series Circuit | 串联电路 | Parallel Circuit | 并联电路 |
|---|---|---|
| Current I | Same everywhere | 各处相同 | Splits across branches; Itotal = I₁ + I₂ + … |
| Voltage V | Splits across components; Vsupply = V₁ + V₂ + … | Same across each branch |
| Total resistance Rtotal | Rtotal = R₁ + R₂ + … | 1/Rtotal = 1/R₁ + 1/R₂ + … |
In a series circuit, adding more resistors increases the total resistance. In a parallel circuit, adding another branch provides an extra path, so the total resistance decreases.
串联电路中增加电阻会增大总电阻。并联电路中增加支路提供了额外电流路径，总电阻反而减小。
7. Electrical Power | 电功率
Electrical power is the rate at which an appliance transfers electrical energy. It can be calculated with the voltage across the component and the current through it.
电功率是用电器转移电能的速率，可用元件两端的电压和通过的电流计算。
P = I V
Combined with Ohm's Law, alternative forms are useful when resistance or current is known.
结合欧姆定律，可以在已知电阻或电流时使用电功率的其他形式。
P = I² R and P = V² / R
Energy transferred by an appliance depends on its power rating and how long it is switched on. Energy consumed is usually measured in kilowatt‑hours (kWh) for domestic electricity supplies.
用电器转移的能量取决于其功率和使用时间。家庭用电常用千瓦时（kWh）计量消耗的电能。
E = P t
8. Wave Properties | 波的特性
A transverse wave has oscillations perpendicular to the direction of energy transfer (e.g., light, water waves). In a longitudinal wave the oscillations are parallel to the direction of energy transfer (e.g., sound).
横波的振动方向与能量传递方向垂直（如光波、水波）。纵波的振动方向与能量传递方向平行（如声波）。
Key wave quantities are frequency (number of waves per second, hertz), wavelength (distance between consecutive crests, metres), amplitude (maximum displacement from the rest position) and period (time for one complete wave).
波的关键物理量包括频率（每秒的波数，赫兹）、波长（相邻波峰间的距离，米）、振幅（离开平衡位置的最大位移）和周期（完成一个完整波形所需的时间）。
All waves obey the wave equation, which links speed, frequency and wavelength.
所有波都遵循波速方程，它将波速、频率和波长联系起来。
v = f λ
Diffraction is the spreading of a wave after it passes through a gap or around an obstacle. The effect is greatest when the gap is about the same size as the wavelength. Refraction is the change in speed (and direction if the wave meets a boundary at an angle) when a wave travels from one medium to another.
衍射是波通过狭缝或绕过障碍物后发生的扩展现象，当缝隙宽度与波长相近时衍射最明显。折射是波由一种介质进入另一种介质时速度改变（若斜射入界面，方向也改变）的现象。
9. Electromagnetic Spectrum | 电磁波谱
⁸ m s⁻¹). In order of decreasing wavelength and increasing frequency, the main regions are: radio, microwave, infrared, visible, ultraviolet, X‑ray and gamma.
电磁波谱包含所有在真空中以光速（3.0 × 10⁸ m s⁻¹）传播的横波。按波长递减、频率递增的顺序，主要区域为：无线电波、微波、红外线、可见光、紫外线、X 射线和伽马射线。
Different regions have different typical sources, detectors and uses. For example, microwaves are used for mobile communications and cooking; infrared is used in thermal imaging; X‑rays are used for medical imaging; gamma rays are used to sterilise surgical equipment.
不同频段的电磁波有不同的来源、探测器和用途。例如，微波用于移动通信和烹饪；红外线用于热成像；X 射线用于医学成像；伽马射线用于消毒手术器械。
All electromagnetic waves transfer energy. As frequency increases, the energy carried by each photon increases, which explains why ultraviolet, X‑rays and gamma rays can be harmful in high doses.
所有电磁波都传递能量。频率越高，每个光子携带的能量越大，因此过量的紫外线、X 射线和伽马射线会对人体造成伤害。
10. Nuclear Radiation and Half-life | 核辐射与半衰期
An unstable nucleus can become more stable by emitting radiation. Three common types are alpha (α), beta (β) and gamma (γ).
不稳定的原子核可以通过发出辐射变得更加稳定。常见的辐射有三种：α（阿尔法）、β（贝塔）和 γ（伽马）。
| Type | 类型 | Nature | 本质 | Ionising power | 电离能力 | Penetration | 穿透力 |
|---|---|---|---|
| Alpha α | Helium nucleus ⁴₂He | High | Stopped by paper or a few cm of air |
| Beta β | Fast electron ⁰₋₁e | Medium | Stopped by a few mm of aluminium |
| Gamma γ | Electromagnetic wave | Low | Reduced by thick lead or concrete |
In α decay the atomic number decreases by 2 and the mass number by 4. In β decay a neutron changes into a proton, so the atomic number increases by 1 while the mass number stays the same.
α 衰变中，原子序数减少 2，质量数减少 4。β 衰变中，一个中子变为质子，原子序数增加 1，质量数不变。
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
¹⁴₆C → ¹⁴₇N + ⁰₋₁e
The half‑life of a radioactive isotope is the time taken for half of the nuclei in a sample to decay, or for the activity to drop to half its original value. It is constant for a given isotope and can be used to date materials.
放射性同位素的半衰期是样品中一半原子核发生衰变所需的时间，或是活度降到初始值一半所需的时间。对特定同位素，半衰期是恒定的，可用于测定材料年代。
11. Gravity and the Universe | 重力和宇宙
Weight is the gravitational force exerted on an object. Near the Earth’s surface the gravitational field strength g is about 9.8 N kg⁻¹.
重量是作用在物体上的重力。地球表面附近的重力场强度 g 约等于 9.8 N kg⁻¹。
W = m g
A satellite remains in orbit when its forward speed balances the pull of gravity, producing a circular (or elliptical) path. Geostationary satellites have a period of 24 hours and stay above the same point on the Earth’s equator.
当卫星的前进速度与重力牵引平衡时，它就能保持在轨道上，形成圆（或椭圆）形轨迹。地球同步卫星的周期为 24 小时，停留在赤道上空的同一点上。
Observations show that light from distant galaxies is shifted towards the red end of the spectrum (redshift), which tells us the galaxies are moving away from us. This supports the Big Bang theory, which describes the universe beginning from a very hot, dense state and expanding ever since.
观测发现，来自遥远星系的光会向光谱的红端偏移（红移），说明这些星系正在远离我们。这为大爆炸理论提供了证据：宇宙起始于一个极高温、极高密度的状态，并一直膨胀至今。
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