Electricity, Electric Charges And Curren Flashcards
What is an atom made out of?
Protons (+)
Neutrons (No charge)
Electrons (-)
What is the condition for electric current to pass round a circuit?
The circuit must be complete (closed)
There must be a source of potential difference I.e battery
What is electric current?
Current The rate of flow of charge in a wire or component.
Electric current is the movement of negative charges in a circuit.
What is a charge carrier?
Charged particles that create current due to its passage are called charge carriers
What is the convention for the direction of current in a circuit?
From positive to negative
What is the symbol for electric charge?
Q
What are electrons?
Electrons are charge carriers that flow in an electric circuit - from negative to positive terminals
What is the charge on a proton?
1.6 x 10 ^-19C
What is the equation for electric charge and what is it measured in?
Q = It
Where Q charge in Couloumbs C
Where I current in Amperes A
And t time takes in seconds s
What does the conservation of charge state?
No net electric charge can be created or destroyed
What is Electricity
Move,ent of charge around a circuit, also referred to as electric current.
What is the unit of current?
The unit is Ampere (A) which is defined in terms of magnetic force between two parallel wires when they carry the same current. The symbol for current is I
What is the equation for current?
I = change in Q/ Change in t
What are the three ways materials can be classified in electrical terms?
Conductors, Insulators or semiconductors
Describe what happens in an insulator.
In an insulator, each electron is attached to an atom and cannot move away from the atom. When a voltage is applied across an insulator, no current passes through the insulator, because no electrons can move through the insulator.
Describe what happens in a metallic conductor.
Most electrons are attached to atoms but some are delocalized - the delocalized electrons are the charge carriers in the metal. When a voltage is applied across a metal, these conduction electrons are attracted towards the positive terminal of the metal
Describe what happens in a semiconductor.
The number of charge carriers increases with the increase in temperature. The resistance of a semiconductor therefore decreases as its temperature is raised.
What makes something a good conductor?
Good conductors allow electrons to move through them easily. Insulators do not allow electrons to move easily.
Describe what happens when a torch bulb is connected to a battery.
When a torch bulb is connected to a battery, electrons deliver energy from the battery to the torch bulb. Each electron moves around the circuit and takes a fixed amount of energy from the battery as it passes through it. The electrons then deliver energy to the bulb as they pass through it. After delivering energy to the bulb, each electron re-enters the battery via the positive terminal to be resupplied with more energy to deliver to the bulb.
What is the function of a battery?
It has the potential to transfer energy . When a battery is in a circuit, each electron passing through a circuit component does work to pass through the component and therefore transfers some or all of its energy. The work done by an electron is equal to its loss of energy. The work done per unit charge is defined as the potential difference or voltage across the component.
What is potential difference? It’s equation?
Potential difference is the work done (energy transfer) per unit charge. It is measured in JC-1 and it’s unit is the Volt.
V= W/Q
Where V (pd) is Volt
W is amount of energy in Joules
And Q is charge in Columbus (C)
What is emf? What is it measured in?
The emf of a source of electricity is defined as the electrical energy produced per unit charge passing through the source.
It is measured in Volts just like Potential difference/
When does an electric current have a heating and magnetic effect?
When it passes through a component with resistance.
What is the equation for Work done in electrical components?
What is the equation for Electrical power?
Work done W= IV x Change in t
Energy transfer is equal to work done.
Since power = energy over time then work done over time will give
P = IV
