WorksheetsModule 2.2
Total questions: 7
Worksheet time: 4mins
A developer is designing a low-cost 3D printer and needs the gantry to move in precise 3.6-degree increments without using expensive external encoders to track position. Which motor type and configuration would best fulfill this requirement?
A brushed DC motor, because its speed is directly proportional to voltage.
A hybrid stepper motor using standard 1.8-degree steps.
A variable reluctance stepper motor with a 30-degree step size using a gearbox.
A brushed DC motor with a high-current battery.
In a standard brushed DC motor, a current-carrying conductor is placed within a magnetic field provided by stator magnets. If the motor suddenly stops rotating despite receiving power, and the magnetic field is intact, what is the most likely electrical failure based on the Lorentz Force principle?
Current has stopped flowing through the armature windings, preventing the production of torque.
The voltage is too high, causing the speed to exceed the limit.
The commutator has reversed the current too quickly.
The motor has reached its holding torque limit.
A robotic lifting platform must hold a heavy package at a specific height against the force of gravity while the system is at rest. Which characteristic of a stepper motor makes it uniquely suited for this static task?
Its ability to rotate at high RPMs for drones.
The proportionality of speed to input voltage.
Its high holding torque, which allows it to maintain a position without movement.
The use of a closed-loop feedback system.
A hybrid stepper motor is designed with 50 rotor teeth and 48 stator teeth. If a design requires the motor to move with even higher resolution than its standard 1.8-degree step, what control technique can be applied without changing the mechanical hardware?
Increasing the DC voltage to the stator coils.
Utilizing the Lorentz force to increase torque.
Half-stepping, which energizes two adjacent coils to settle the rotor in between steps.
Switching from a closed-loop to an open-loop system.
A factory uses a conveyor belt to move fine chemical flour, which creates a highly combustible dust-filled environment. Why is a brushed DC motor considered a significant safety hazard in this specific application?
It is too slow to move the flour efficiently.
The friction between the brushes and the commutator can create sparks.
It requires a closed-loop circuit which is prone to leakage.
The Lorentz force creates a high-pressure zone around the shaft.
A CNC machine operator notices that as they increase the speed of the stepper motors to finish a job faster, the motor begins to miss steps and lose accuracy. Based on known disadvantages, what is the cause?
Stepper motors have no holding torque at high speeds.
The voltage is not high enough to sustain the Lorentz force.
Stepper motor torque drops significantly as speed increases.
The open-loop system requires a feedback encoder to maintain speed.
What would happen to a brushed DC motor's rotation if the commutator failed to reverse the current every half-turn?
The motor would double its speed because the current is continuous.
The motor would change from an open-loop to a closed-loop system.
The torque would not stay in the same direction, and the shaft would cease to rotate continuously.
The motor would naturally become a variable reluctance stepper motor
