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填空题
人们常用手机进行“自拍”，手机镜头相当于一个____透镜；“自拍”时，手机镜头到人的距离应____(填“大于”“小于”或“等于”)透镜的二倍焦距．
参考答案
参考解析
解析：
手机拍照与照相机原理相同，手机的镜头相当于一个凸透镜，成倒立、缩小的实像，所以手机镜头到人的距离应满足大于二倍焦距的条件．
手机拍照与照相机原理相同，手机的镜头相当于一个凸透镜，成倒立、缩小的实像，所以手机镜头到人的距离应满足大于二倍焦距的条件．
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