4 Factors which Speed up a Simple D.C Electric Motor

Question 1

4 factors which speed it up:

Answer 1

More current
More turns on the coil
Stronger magnetic field
A soft iron core in the coil

Question 2

Look at the diagram page 62 to answer questions

Answer 2

Ok

Question 3

1) What does the diagram show?

Answer 3

The forces acting on the two side arms of the coil

Question 4

2) What are these forces?

Answer 4

Just the usual forces which act on any current in a magnetic field

Question 5

3) Why does it rotate?

Answer 5

Because the coil is on a spindle and the forces act one up and one down

Question 6

4) The split-ring commutator is a clever way of doing what?

Answer 6

Swapping the contacts every half turn to keep the motor rotating in the same direction

Question 7

5) How can the direction of the motor be reversed?

Answer 7

Either by swapping the polarity of the d.c supply or swapping the magnetic poles over

Question 8

6) How can the speed be increased?

Answer 8

By adding more turns to a coil, increasing the current, increasing the strength of the magnetic field or by adding a soft iron core

Question 9

7) How can you work out which way the coil will turn?

Answer 9

Using Fleming’s left-hand rule