6a Flashcards
Charge v charge carrier
charge a fundamental property of subatomic particles responsible for electric interaction
charge carrier a charged particle that contributes to an electric current
Conventional current v electric current
conventional current the (hypothetical) direction of flow of positive charge
current (electric) the rate of movement of charge with respect to time, requiring the
movement of charged particles
Direct current
direct current (DC) electric current that flows in one direction around a circuit
Electric potential energy v potential difference
electric potential energy potential energy due to the separation of charge
potential difference the difference in electric potential energy per unit charge between
two points
Power v voltage
power the rate of change of energy with respect to time
voltage see potential difference
Electrical quantities
The quantities of electric charge (Q), potential difference (V ), current (I ), energy (E ), and power (P)
How does charge (Q) describe electricity
Electric charge, Q, is a fundamental property of particles (such as protons and
electrons) that is responsible for all electric interactions. Charge is measured
in coulombs (C ) and can be either positive or negative. Charge cannot be passed
between particles, created or destroyed. It can only be carried through space
by the movement of the particles themselves.
The term electricity is a general term used to refer to the physical interactions
associated with the presence or movement of charge.1
Hair up from balloon explanation
Static electricity is the stationary separation or imbalance of electric charge in
an object. Some physical interactions can move the charged particles in a material.
For example, rubbing a balloon on human hair transfers electrons from the hair
onto the rubber balloon. This gives the balloon a net negative charge and the hair is attracted to the balloon
How does potential difference (v) deceive electricity
Due to the electrostatic force, charges attract and repel each other without contact.
This means that depending on the position of a charge relative to other charges,
it has the potential to gain energy when other charges push or pull it.
The potential of a charged particle to gain energy due to other charges is called
electric potential energy. The difference in electric potential energy per coulomb
between two locations is called the potential difference, V. The symbol ‘ε’ can also
be used to represent potential difference.
Potential difference can be related to electric potential energy and charge
Ideal source of potential energy
Ideal sources of potential difference, like cells, batteries, and certain power supplies,
provide the same potential difference no matter what circuit they are applied to.
The potential difference only depends on the source.
One of the common sources of potential difference in electric circuits is a cell.
Cells use chemical reactions to separate positive and negative charges, giving them
electric potential energy and therefore creating a potential difference. This is shown
How does current (I) deceive electricity
When a potential difference is provided to an electric circuit, it causes an electric
current, I , to flow. The current at a point is the rate that charge flows past that point,
and can be calculated using the following formula or the formula triangle in Figure 5.
Most common form of electric current
The most common form of electric current is the flow of electrons through
metallic wires.
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Electrons are repelled from the negative terminal of a voltage source, as like
charges repel, and electrons are attracted towards the positive terminal of a
voltage source, as opposite charges attract.
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Electrons are free to move in metallic wires.
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Therefore the electrons travel from the negative terminal to the positive terminal,
as shown in Figure 6.
How does power (p) describe electricity
Electric potential energy can be transformed into other forms of energy like light,
thermal energy, movement, and sound by electrical components.
Electric circuits usually involve the transformation of energy between various forms.
Figure 8 shows how the chemical energy stored inside a battery is used to create
a potential difference, giving electric potential energy to charge carriers in the wire, which is then transferred by the light bulb into light and thermal energy
Power, P , is the rate of transfer of energy with respect to time, and can be calculated
using the following formula or the formula triangle in Figure 9. The total amount of
power delivered to a circuit is always equal to the total amount that is consumed by the circuit components
Hydraulic circuit analogy
Water pump: potential difference source (cell , power supply) (pushed around circuit like potential difference source drives electric current)
Piping: wire
Valve: switch
Water wheel: power consuming component (uses pump energy or potential difference)
Highway circuit analogy
Petrol station: potential difference source (provide energy to push or charge to carry around
Roads: wires
Draw Bridges: switch
