MODULE 6 IQ 4

Question 1

What are DC motors

Answer 1

A device which converts electrical energy into mechanical energy

Question 2

Components of a DC motor

Answer 2

Rotor, stator,. Brushes, split-ring commutator

Question 3

What is in a rotor

Answer 3

Armature, coil

Question 4

What is an armature

Answer 4

The frame around which the coil of wire is wound. It has an axis which it can freely rotate

Question 5

What is a coil

Answer 5

One or more turns of wire wound around the armature. The coils carry current which generate a force to produce the rotational effect known as torque

Question 6

What is a stator

Answer 6

The stationary magnets that provides the external magnetic field around the coils

Question 7

What are brushes

Answer 7

Do cutting contact that connect the external circuit to the split-ring commutator

Question 8

What is a split-ring commutator

Answer 8

A device with 2 metal semicircular rings that reverses the direction of the current flowing through the coil at every half rotation (whenever it passes the vertical position), allowing the rotor to continuously rotate in the same direction

Question 9

Torque in a DC motor in the horizontal position

Answer 9

τ = BIA

τ: torque
B: magnetic field strength
I: current
A: area of coil

Question 10

Torque in a DC motor at an angle

Answer 10

τ = nBIAsinθ

τ: torque (Nm)
N: number of coils
B: magnetic field strength (T)
I: current (A)
A: area of coil (m^2)
θ: angle between the plane of the coil and the normal to the magnetic field

Question 11

What is back EMF

Answer 11

Induced voltage produced in the coil of a motor due to its rotation in a magnetic field