Final answer:
Swapping the electrical connections to the battery will not increase the speed of a d.c. electric motor, but increasing the strength of the magnet, lubricating the moving parts, and using a wire with lower electrical resistance can increase its speed.
Step-by-step explanation:
In a d.c. electric motor, swapping around the electrical connections to the battery which powers the motor will not increase the speed at which the motor rotates. The direction of current flow determines the direction of the magnetic field and the resulting torque on the motor. By swapping the electrical connections, the current direction would change, but the torque on the motor would remain the same.
Increasing the strength of the magnet inside the motor can increase the speed at which the motor rotates. This is because a stronger magnetic field will exert a greater torque on the motor.
Lubricating the moving parts of the motor can reduce friction, allowing the motor to rotate more easily and potentially increase its speed.
Replacing the wire which forms the coil with a type of wire that has a lower electrical resistance can also increase the speed of the motor. A lower resistance wire allows more current to flow through the motor, resulting in a stronger magnetic field and greater torque.