Electric
motors
Group 4
Hair and beauty
appliance
3 conversions:
1. Electricity -> Heat (thermal energy)
by circulating electricity through a resistor.
2. Electricity -> Kinetic - To move the air out
3. Waste energy: Sound + Heat that is not
absorbed by the air
The motor used in hair dryer is a small
permanent magnet DC motor. This is because
the motor runs at a high speed (1800020000 rpm) which is not possible by small
AC motors which are generally shaded pole
motors whose speed is limited
by frequency.
Kitchen appliance
Electrical -> Radiation energy
(microwaves and thermal
energy) due to the resistance
of the wires.
The radiation energy is
absorbed by the food which
changes it to thermal energy.
Waste energy: thermal energy
(into air), light energy, sound
energy
Transportation
These motors
convert electrical
energy, stored in
batteries, into
mechanical energy,
which makes the
wheels of the
motorbike move.
Industry
When we switch on a fan, the fan
converts a significant portion of
the electrical energy -> kinetic
energy of the fan blades. Some
part of electric energy is
converted into heat and sound.
Music
Electrical energy -> sound energy. It
produces a sound wave
corresponding to the pattern of the
original speech or music signal.
Electrical energy vibrates a
loudspeaker diaphragm that in turn
vibrates the air in immediate contact
with it.
Waste energy: Thermal energy
Used in surgery
The motor in a surgical tool to make incision
Turns electrical energy into kinetic energy (Spinning the rod)
Waste energy:
- Heat
- Sound
How to increase
strength
- A stronger current which makes
the electromagnet stronger
- A stronger magnet (which
produces a denser magnetic field)
- More turns on the coil
How motor
works?
A current carrying conductor will
have a magnetic field which will
interact with the permanent magnet
=> Therefore, producing a force.
Thank you
very much!
Any question?