Module 4 Flashcards
Kirchhoff first law
Sum of currents entering a junction is equal to the sun of the currents leaving a junction
Emf
Energy gained per unit charge by charges passing through a supply
Potential difference
Energy gained per unit charge by charges passing through a component
Ohms law
The current through a conductor is proportional to the potential difference across it
Resistance is proportional to:
- material
- length of wire
- cross sectional area
- temperature
A kilowatt hour
1000 watts for 3600 seconds, 3.6 million joules
Kirchoffs second law
Sum of the emf is equal to the sum of the products of the current and resistance
For a series circuit
- the current has the same value at any point
- emf = sum of pd across resistors
- resistance = sum of individual resistors
For a parallel circuit
- components in each branch share same voltage as the cell
- total current = sum of branch currents
- 1/total resistance = 1/ sum of the individual resistors
Terminal pd
The potential difference across a cell
Intensity
The power transmitted per unit area
During refraction
A wave will change its speed and may change direction
Interference
The addition of two or more waves that results in a new pattern
The principle of superposition
When two or more waves of the same type meet, the resultant wave can be found by the adding the displacements of the individual waves
A quantum
A small discrete unit of energy
A photon
A quantum associated with electromagnetic radiation
An electron volt
The kinetic energy gained by an electron when it is accelerated through a potential difference of 1V
Threshold frequency
The lowest frequency of radiation that will result in the emission of electrons from a particular metals surface
Work function of a metal
The minimum energy required to release an electron from its surface
Nodes
Points in a stationary wave at which there is no displacement of the particles at any time
Antinodes
Displacement of particles in a stationary wave varies by the maximum amount
Photoelectric effect explanation
When visible light is incident on a negatively charged plate there is no movement of the gold lead
However when uv light is shone on the negatively charged zinc plate, the gold leaf falls
This shows the metal plate loses its negative charge through the emission of electrons.
