AC Generators
Which way do magnetic field lines point
North to South
Give an example of a power source that generates a DC current
Battery
What is the scientific name for Solid --> Liquid state change?
Melting
State the equation for acceleration
a = change in velocity divided by time
a = delta V / t
This states that energy cannot be created or destroyed
What is the conservation of energy ?
What happens when a magnet is moved near a wire?
A current is induced
Electricity is induced
Describe the motion of electrons in a DC circuit
One direction (negative to positive terminals of a battery)
When a solid is heated, its volume...
increases
This is the equation for Force
F = ma
Convert the following into standard form : 54000 m
5.4 x104 m
Back and forth / always changing direction
Name something that increases the turning force in a DC motor
1. increase the current
2. increase the magnetic field strength
3. increase the number of coils
Finish the sentence
In a closed container, when the temperature of a gas increases but volume stays the same, its pressure...
...increases.
This is the equation for Pressure
P = F / A
Pressure = Force / Area
Pressure = Force / Cross sectional area
Convert the following into standard form: 0.00978 s
9.78 x10-3 s
These keep the coil in constant electrical contact with the carbon brushes of a AC generator
What are slip-rings?
A DC motor has its current reduced. Describe what will happen to the turning force on the current carrying wire
It will decrease
Finish the sentence
In a closed container, when the volume of a gas increases and temperature stays the same, the pressure...
...decreases.
This is the equation for Power
"Work done / time" OR "Change in energy / time"
As an object is heated, it's density...
decreases
Name the function of the carbon brushes in an AC generator
To keep constant electrical contact between the circuit and slip rings
Describe the function of a split ring commutator
This allows the coil to rotate 360 degrees and the current to flow in a single direction
State the equation for Specific Heat Capacity (Hint: units are J/kgK)
C = E / ( 'm' * 'delta T')
Specific Heat Capacity = Energy / (mass*temperature change
What is the equation for efficiency
Useful energy input / total energy output
(Useful energy input / total energy output) *100%
Useful power input / total power output
(Useful power input / total power output) *100%
Define spring constant
Spring constant 'k' determines how stiff a spring is.
k = Force / extension