Chapter 8: Charge and Current Flashcards
What is the definition of Electric Current, and what is its equation?
Electric Current is defined as the rate of flow of charge, and its equation is:
I = Q / t
The Unit of Current is Amps and One Amp is defined as 1 Coulomb of Charge passing a fixed point per second.
What is the definition of the Coulomb?
One Coulomb is defined as the amount of charge that passes a point in one second when there is a current of 1A.
What is the value of Elementary Charge, and what particles hold charge?
Elementary Charge has the value of 1.6x10^-19 C for Charge Carriers with a +1e charge (Protons and Electrons). Charge Carriers with a higher charge will have a Charge of n x 1.6x10^-19 C (where ‘n’ is the relative charge).
What is the equation that links Charge, Number of Charge Carriers (electrons) and Elementary Charge?
The Equation that links Charge, Number of Electrons (or Charge Carriers) and Elementary Charge is:
Q = ne
Charge = Number of Charge Carriers x 1.6x10^-19
What happens to the Electrons and Positive Ions when current flows through a Conductor?
When Current flows in a Conductor, the Delocalised Electrons flow from the Positive end to the Negative end. The positive ions do not move however they vibrate within their fixed positions.
What happens to the Positive Ions within a Metal when Temperature increases?
When Temperature increases, the Positive Ions within the Conductor vibrate more vigorously within their fixed position.
What Factors affect the current?
Factors that can affect Current include:
- More Electrons flowing past a fixed point per second due to larger surface area.
- Same Number of Electrons moving faster through a fixed point within the metal.
What direction does Current flow?
Current within a circuit flows from the Positive Terminal to the Negative Terminal.
What are the name of Liquids that can carry current?
Liquids that can carry Current are called Electrolytes.
Why do Ammeters contain a very low resistance?
Ammeters contain a very low resistance so that they can reduce the effect the component has on the current whist measuring its Value.
What is Kirchoff’s First Law, and what is conserved?
Kirchoff’s First Law states that for any junction within an electrical circuit, the Total Current going into a Junction is the Total Current going OUT of the Junction.
In Kirchoff’s First Law, Charge is conserved.
What is the Law of Conservation of Charge?
The Law of Conservation of Charge states that Charge cannot be created or destroyed, and the Total Charge within a Closed System remains constant.
What is the definition of Number Density?
Number Density is defined as the Number of Free Electrons per Cubic Metre within a material. The higher the number density, the greater the conductivity.
What is the definition of Mean Drift Velocity?
Mean Drift Velocity is defined as the Mean Velocity of Charge Carriers flowing within a material or wire. Measured in ms-1.
What is the Equation that links Current, Cross-sectional Area of Material, Number Density, Elementary Charge, and Mean Drift Velocity?
The Equation that links Current, Cross-sectional area, Number Density, Elementary Charge and Mean Drift Velocity is:
I = A n e v
I = Current, A = Cross-sectional Area, n = Number Density, e = Elementary Charge, v = Mean Drift Velocity.
