Project Research And Planning – Heat Loss Through Cooling Curves
Unit 6: investigative Project
A: Understand electrical symbols, units, definitions, relationships and properties of circuit
components for use in the construction of circuits
B: Construct series and parallel circuits for use in standard electrical applications and measure
electrical values
Current (ampere): Electrical current is the flow (movement) of electric charges. For an electric charge to
flow there has to be a source of potential difference and a closed (or complete) circuit. An electric
, current is the flow (movement) of electric charges. Electric current is measured in amperes (A). The flow
of charge (C) = current (A) x time (s). A current has the same value at every point in a single closed loop.
The current is equal to the charge divided by the time. I = Q/T
Potential difference (volt): Potential difference is the difference in the amount of energy that charge
carriers have between two points in a circuit. Measured in Volts: Potential difference (p.d.) is measured
in volts (V) and is also called voltage. The energy is transferred to the electrical components in a circuit
when the charge carriers pass through them. We use a voltmeter to measure potential difference (or
voltage).Potential Difference formula:** V = I x R** The potential difference (which is the same as
voltage) is equal to the amount of current multiplied by the resistance. A potential difference of one
Volt is equal to one Joule of energy being used by one Coulomb of charge when it flows between two
points in a circuit.
Electrical charge (coulomb): The SI unit of charge, the coulomb, is the quantity of electricity carried in 1
second by a current of 1 ampere. Conversely, a current of one ampere is one coulomb of charge going
past a given point per second. In general, charge Q is determined by steady current I flowing for a time t
as Q = It.
Resistance (ohm): Resistance is a measure of how much a component decreases the current. The bigger
the resistance, the smaller the current. Resistance is measured in ohms (symbol Ω). V=IR
Conductance (Siemen): Conductance is the measure of how easily electricity flows along a certain path
through an electrical element, and since electricity is so often explained in terms of opposites,
conductance is considered the opposite of resistance. In terms of resistance and conductance, the
reciprocal relationship between the two can be expressed through the following equation: R = 1/G,
G=1/R; where R equals resistance and G equals conduction. Another way to represent this is: W=1/S,
S=1/W, where W (the Greek letter omega) represents resistance and S represents Siemens, ergo the
measure of conductance. In addition, Siemens can be measured by comparing them to their equivalent
of one ampere (A) per volt (V).
Electrical power (watt): Power is the rate at which work is done or energy is transferred in a unit of
time. Power is increased if work is done faster or energy is transferred in less time. The equation for
power is P = W/t. P stands for power (in watts), W stands for the amount of work done (in Joules) or
energy expended (in Joules), t stands for the amount of time (in seconds). Power is measured in energy
(joules) divided by time. The SI unit of power is the watt (W) or joule per second (J/s). Power is a scalar
quantity, it has no direction.
Capacitance (farad and sub-units): The property of an electric circuit or its element that permits it to
store charge, defined as the ratio of stored charge to potential over that element or circuit (Q/V); SI unit:
farad (F).
Electromotive force (EMF) as a measure of ratio of energy supplied per unit of charge: Electromotive
force is defined as the electric potential produced by either electrochemical cell or by changing the
magnetic field. EMF is the commonly used acronym for electromotive force. A generator or a battery is
used for the conversion of energy from one form to another. In these devices, one terminal becomes
positively charged while the other becomes negatively charged. Therefore, an electromotive force is a
work done on a unit electric charge. The electromotive force symbol is ε. The formula is ε = V + Ir. The
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