Câu 1: Có hai thanh kim loại A, B bề ngoài giống hệt nhau, trong đó một thanh là nam châm. Làm thế nào để xác định được thanh nào là nam châm? A. Đưa thanh A lại gần thanh B, nếu A hút B thì A là nam châm. B. Đưa thanh A lại gần thanh B, nêu A đẩy B thì A là nam châm. C. Dùng một sợi chỉ mềm buộc vào giữa thanh kim loại rồi treo lên, nếu khi cân bằng thanh đó luôn nằm theo hướng Bâc - Nam thì đó là thanh nam châm. D. Đưa thanh kim loại lên cao rồi thả cho rơi, nếu thanh đó luôn rơi lêch về một cực của Trái Đất thì đó là nam châm. Câu 2: Một nam châm vĩnh cửu có đặc tính nào dưới đây? A. Khi bị cọ xát thì hút các vật nhẹ. B. Khi bị nung nóng lên thì có thế hút các vụn sắt. C. Có thể hút các vật bằng sât. D. Một đầu có thể hút, còn đầu kia thì đẩy các vụn sắt. Giả hộ mink với và giải thích nha vì nam châm đẩy nhau khi ngược chiều và hút nhau khi cùng chiều Lực hướng tâm luôn hướng về em, em chính là tâm. nhớ vk 😔😔😕😕

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