Electricity Flashcards
EMF
The energy supplied to each coulomb of charge as it passes through the power supply
What is the short circuit current?
When Vtpd and resistance is zero.
What is the conduction band?
The outermost band, with the highest energy.
When can a material conduct?
When the conduction band is partially filled.
What happens when the conduction band is full?
It becomes the new valence band and a new, higher energy, conduction band is formed.
When can a material not conduct?
If there are no electrons in the conduction band.
What are the properties of insulators?
There are no electrons in the conduction band.
The band gap between the conduction and valence band is too large for electrons to move from valence to conduction.
What are the properties of conductors?
There is no gap between the conduction band and the valence band.
The conduction band is partially filled.
What bias allows for current to flow in a diode?
Forward bias
What does the capacitor graph for charge and voltage look like?
Linear, positive gradient. Standard straight line graph
What does the charging a capacitor graph look like for current against time?
Curve, negative gradient, gradient getting closer to zero before hitting x-axis.
What does the charging a capacitor graph look like for charge against time?
Positive curve that levels off. Gradient getting closer to zero, then graph becomes straight horizontal line.
What does the voltage over a charging capacitor look like on a graph?
Positive curve that levels off. Gradient getting closer to zero.
Opposite for voltage over resistor.
What does the capacitor discharging graph look like for current over time?
Below x-axis. “Positive” curve. gradient getting closer to zero, levels off when y is zero.
What is the depletion layer?
The middle section of a p-n junction where electrons and holes combine. This creates a potential barrier. Therefore, work needs to be done to allow electrons to move from n-type to p-type.
How do electrons move through diodes?
By moving from the conduction band of the n-type to the conduction band of the p-type. Electrons drop in the depletion layer to the valence band
How do LEDs emit light?
A voltage applied causes electrons to move towards the conduction band of the p-type from the n-type. Electrons drop from conduction band to the valence band, which emits a photon.
What is the photovoltaic effect?
When electrons in a p-n junction gain energy from photons, causing them to move from the valence band to the conduction band. Electrons move towards n-type, producing a potential difference.
