Ultrasound has a frequency higher than 20,000 Hz and are unable to be heard by humans
Uses: pre natal scanning and cleaning- vibrations knock dirt off
the longer the ultrasound takes to read a detector, the further away the object is.
Frequency- the number of waves that pass a point each second.
Height on an oscilloscope trace = amplitude
Sound- Longitudianal Waves
Sound waves cannot travel through a vaccum. This requires particles
Sound is produced by mechanical vibrations.
Sound waves can be reflected and refracted.
Humans can hear sound waves between 20Hz- 20,000Hz
Electromagnetism- Motor Effect
Split ring ammutator- keeps the coil rotating
Brushes- connect the slip rings to the circuit.
When a wire is placed in a magnetic field, it experiences a force.
The force is greatest when the wire is perpendicular to the magnetic field
The force is 0 when the wire is parallel to the magnetic field because the magnetic field is not cut.
The force acts on both sides of the coil. this causes the coil to turn when a current passes through.
Electromagnetism- Motor Effect, Uses
When a current passes through the coil it vibrates due to a force due to the motor effect.
The current change direction therefore the force changes direction back and forth causing the diaphgram to vibrate.
Objects moving in a circular path e.g a rubber bung spun clockwise, a car going around a roundabout.
Its velocity changes direction producing an acceleration toward the centre. the centripetal force is due to friction.
To stay in orbit at a certain distance, objects must have a certain speed.
Factors affecting Centripetal Force:
Increasing mass Increasing speed Increasing the radius
Turning Forces- Gravitational Attraction
The earth, sun, moon and other orbits attract each other with a force called gravity.
Gravitational Force provides the centripetal force that allows planets and satellites to stay in circular orbits.
Factors affecting Gravity
The bigger the mass, the greater the force of gravity
The bigger the distance, the smaller the force of gravity