Definition: Flow of electric charge.
Unit: Ampere (A) or Amps.
1 A = 1 coulomb per second.
Current Flow:
Defined as the flow of positive charges, despite electrons flowing in the opposite direction.
Electron Flow: Actual flow of electrons (opposite of current direction).
Types of Current:
Direct Current (DC): Flows in one direction (e.g., battery-operated devices).
Alternating Current (AC): Changes direction (e.g., electricity in homes and schools).
Definition: Materials through which charge can flow easily.
Characteristics:
Usually metals (e.g., copper, silver).
Possess free electrons that move easily.
Definition: Materials through which charge cannot flow easily.
Examples: Wood, plastic, rubber, dry air.
Characteristics:
Bound electrons that do not move easily.
Definition: Opposition to the flow of charges in a material.
Measurement: Measured in Ohms (Ω).
Factors Affecting Resistance:
Thickness: Thicker materials have lower resistance.
Length: Shorter materials have lower resistance.
Temperature: Lower temperatures generally mean lower resistance (superconductors).
Resistors: Objects with resistance that convert electrical potential energy into other forms of energy (e.g., light or heat from a light bulb).
Definition: Difference in electric potential between two locations in a circuit or electric field.
Measurement: Measured in Volts (V).
Electric potential energy per charge.
Sometimes referred to as potential difference.
1 V = 1 Joule per coulomb.
Voltage Flow: Current flows naturally from high voltage to low voltage. Voltage decreases as charge flows through the circuit, being converted to other forms of energy.
Function: Increase electric potential energy of electric charges.
Examples:
Batteries: Convert chemical energy to electrical energy.
Solar Cells: Convert sunlight to electrical energy.
Generators: Convert mechanical energy to electrical energy.
Formula: V = IR, where V = Voltage, I = Current, R = Resistance.
Manipulations:
I = V/R (current = voltage/resistance).
R = V/I (resistance = voltage/current).
Safety Devices:
Fuses, circuit breakers, Ground Fault Circuit Interrupter (GFCI).
Grounding: Grounding prong in plugs.
Personal Safety Practices:
Avoid touching exposed wires.
Do not interact with electrical devices using wet hands.
An electric circuit must have a source of electrical energy and devices run by that energy.
If one element fails, the whole circuit stops working.
Voltage adds up across each device ( V_total = V_1 + V_2 + V_3 + ...).
Resistance adds as well ( R_total = R_1 + R_2 + R_3 + ...).
If one element fails, others can still operate.
Voltage remains the same across all devices ( V_total = V_1 = V_2 = V_3 ...).
Current divides among the branches.
Power: Calculated as voltage multiplied by current (P = VI).
Electrical Energy: Given by the equation E = Pt (energy = power x time).
Formulas:
Watts = Volts x Amperes.
Joules = Watts x Seconds.
Average cost calculated using the formula: Cost = (Energy used in kWh) x (Cost per unit in $/kWh).
Voltage: Adds up across components; V_total = V_1 + V_2 + V_3 ...
Current: Same through all components; I_total = I_1 = I_2 = ...
Resistance: Adds up; R_total = R_1 + R_2 + R_3 ...
Voltage: Same across all branches (V_total = V_1 = V_2 = ...).
Current: Splits across branches; I_total = I_1 + I_2 + I_3 ...
Resistance: Calculated using the reciprocal formula: 1/R_total = 1/R_1 + 1/R_2 + 1/R_3 ...