Providing an on-board power supply is difficult, however, so he is investigating the use of external magnetic fields to power the device.

然而，倘若板载动力装置很难实现的话，他正在研究利用外部磁场给器件提供动力的途径。

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This is a specially designed magnet that allows an operator to steer the capsule around using external magnetic fields generated in a belt worn by the patient when he is being examined.

它是由一个特制的磁体制成，患者接受检查时会佩戴一条带子以产生一个外部磁场，这样医生就可以通过这个外部磁场来控制胶囊的方位。

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Most materials, including milk and water, are diamagnetic, which means they are repelled by external magnetic fields-though this phenomenon is far too subtle to be observed in normal circumstances.

大多数物质，如牛奶和水都是反磁体，即他们会排斥外来磁场，这种现象很微弱，在常规条件下是几乎是观察不到的。

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Most materials, including milk and water, are diamagnetic, which means they are repelled by external magnetic fields though this phenomenon is far too subtle to be observed in normal circumstances.

ECONOMIST: Monitor