Nantong EDM recruitment

(1) DC motor M(3.0V, 1W), that is, the maximum current during normal operation is 1A, so the ammeter (0-0.6A, 0.5ω) is enough, and the ammeter (0-3A, 0. 1ω) is enough.

This problem does not need to measure time or length with vernier caliper, so H and N are redundant.

Therefore, the redundant equipment belongs to DHN. ..

(2) The experimental circuit diagram is shown on the right:

(3) According to the law of conservation of energy: the electric power input to the motor is equal to the first electric heating power of the motor plus the output power of the motor, so

P heat =uI-GV?

According to the paper tape analysis, the speed of uniform motion is: v = XT = 2.20× 10? 20.04=0.555m/s？

(4) Because pHeat =I2RA, the slope of theoretical gRAph of pHeat -I2 graph represents the resistance ra of the coil, and the reason why the slope of actual graph increases is that the resistance in the coil increases with the increase of temperature.

So the answer is; ( 1)DHN

(2)P heat =uI-GV

0.55 m/s

(3) The resistance in the coil increases with the increase of temperature.