Answer :
220-dc motor powered by a 5.3 ohm armature whose resistance is running at its operating speed the series resistance would be necessary to keep the initial current under 20 A
Distance travelled in a unit of time is referred to as speed. It is the rate of movement of an object. Speed is a scalar quantity and the velocity vector's magnitude. There is no clear direction to it. An object is travelling more quickly if its speed is higher. Slower motion is indicated by a lower speed. In simple words, we define speed or velocity as the distance travelled in a specific amount of time. If an automobile is driving faster if its speed is higher. A slow vehicle has less speed, as we say. if an object moves quickly.
Req = R + r = 2 + r
Req = V/I2 + 2 + r = 220/30 60 + 30 r = 220 30 r = 160 r = 5.3 ohm
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