Fig. 1 shows a simplified electric winch used on a rescue boat. Current flows through the armature coil, producing rotation that winds a rope around a drum....
Question 1 Report
Fig. 1 shows a simplified electric winch used on a rescue boat. Current flows through the armature coil, producing rotation that winds a rope around a drum. The battery is connected through a switch and a reversing contactor. The permanent magnets are fixed to the motor case. During a rescue, the winch must lift equipment quickly, but a high current can heat the coil. The crew compares two possible upgrades: a stronger magnet or a coil with more turns in the magnetic field.
(a) What is the armature in this motor? [1]
(b) What effect does increasing the number of turns have on the turning effect? [2]
(c) When the contactor reverses the battery connections, explain why the drum rotates in the opposite direction. [3]
Answer Details
(a) The armature is the rotating coil [1].
(b) More turns mean more wire sides experience magnetic force [1], so the total turning effect increases [1]. [2 marks]
(c) The contactor reverses the battery connections [1], so current in the armature coil reverses [1]. The magnetic forces reverse, so the turning effect and drum rotation reverse [1]. [3 marks]
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