Answers for the Teacher Only

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What Do You Think?

The first telegraph, developed in 1832, worked by sending a current through a coil wrapped around a compass. The current created a magnetic field that exerted a torque on the compass, which then oscillated back and forth for a certain time before settling down and pointing in one direction. The time required for these oscillations to die away limited the speed of sending messages. Replacing the compass with an electromagnet improved the speed substantially.