小树带着展品地图去找旧港口。阴天看不到太阳，针为什么仍会转？Mia follows an exhibit map to an old harbour. Why does a compass still turn under cloudy skies?
第 1 步：针追随磁场Step 1: A needle follows a field
先看针，而不是地图。Look at the needle before the map.
磁针能绕轴转动。地球磁场对它产生作用。针会大致沿当地磁场排列。红端通常标示磁北方向。A magnetic needle can turn around a pivot. Earth’s magnetic field acts on it. The needle approximately aligns with the local field. The marked red end usually indicates magnetic north.
第 2 步：磁北不等于真北Step 2: Magnetic north is not true north
针指出的北，和地图一样吗？Is the needle’s north the same as the map’s?
地图常以真北为方向基准。磁北与真北之间有夹角。这个夹角叫磁偏角。它随地点和时间变化。Maps often use true north as a reference. Magnetic north can point at an angle to it. That angle is called magnetic declination. It varies with location and time.
知道方向，就知道自己在哪里吗？Does knowing direction reveal your position?
方向不是位置。导航还要结合距离和地标。附近磁铁或钢铁会干扰磁针。读数异常时应交叉核对。Direction is not position. Navigation also uses distances and landmarks. Nearby magnets or steel can disturb a needle. An unexpected reading needs cross-checking.
🎮 机制实验室：观察，再判断🎮 Mechanism lab: observe, then decide
无干扰时，角差来自磁偏角；开干扰后额外偏转二十度，仅为示意。Without interference the angle is declination. Switching interference on adds an illustrative 20 degrees.
一句话记住它：Remember it:指南针提供磁方向，定位还需要其他证据。A compass provides magnetic direction; position requires more evidence.
磁针能绕轴转动。A magnetic needle can turn around a pivot.地图常以真北为方向基准。Maps often use true north as a reference.方向不是位置。Direction is not position.
磁学：较高把握。实际磁偏角须用当地当时的数据；故事不用于户外安全导航。High confidence in magnetism. Real declination requires local, dated data; this story is not an outdoor navigation guide.
核对日期：2026 年 10 月 6 日。文字与配图由 AI 生成；已做来源核对及程序测试，待人工复核。Checked 6 October 2026. Text and illustrations are AI-generated. Sources and software checks were performed; human review is pending.
Back to tree
