<p style="text-align: left;">Đặt kim nam châm trên giá thẳng đứng như mô tả trên hình 21.1.<img class="wscnph" style="float: right;" src="data:image/png;base64,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" width="177" height="151" /></p>
<p>+ Khi đã đứng cân bằng, kim nam châm nằm dọc theo hướng nào? </p>
<p>+ Xoay cho kim nam châm lệch khỏi hướng vừa xác định, buông tay. Khi đã đứng cân bằng trở lại, kim nam châm còn chỉ hướng như lúc đầu nữa không? Làm lại thí nghiệm hai lần và cho nhận xét. </p>
<p style="text-align: center;"><span style="text-decoration: underline;"><strong>Hướng dẫn</strong></span></p>
<p style="text-align: left;">+ Khi đã đứng cân bằng, kim nam châm nằm dọc theo hướng Bắc - Nam địa lí. Hình 21.1 </p>
<p style="text-align: left;">+ Kim nam châm vẫn nằm dọc theo hướng ban đầu. </p>
<p> </p>