General Physics 2: Charge

• Study notes for General Physics 2
• These notes are for the 3rd Quarter Review

Charge

• Charge is a fundamental physical quantity responsible for electrical phenomena
• The unit for charge is the Coulomb (C)
• Net charge is the sum of all positive and negative charges in an object
• Triboelectric series shows a list of materials that shows their capability to hold electrons upon gaining them, and their capacity to lose electron when subjected to friction
• The law of conservation of charge states if a system starts with equal charge distributions, the system will be in a state of equilibrium, unless a charge is added or removed from the system
• This law was developed by Benjamin Franklin
• Coulomb's Law: product of two (2) charge values multiplied to a proportionality constant, and divided by the square of the distance between the charges
• An electric field exists in a region around a charged particle
• It is a region associated to each point in space where the Coulomb force will be experienced
• Gauss' Law relates the electric field at all points on a closed surface and the total charge enclosed within the surface
• A Gaussian surface is a hypothetical surface immersed in an electric field that may or may not enclose a charge
• Electric flux is the strength of an electric field over an area in a field region
• A proton refers to a particle with an outward force
• An electron refers to a particle with an inward force
• A neutron has a charge equal to 0
• Equipotential surface describes a region in space where points in the electric field have equal potential, represented by lines surrounding the point charge
• Electric potential energy is potential energy due to a moving charge changing displacement within a projected electric field provided by a rest charge
• Electric potential, also known as voltage, is electric potential energy per unit charge, which arose due to the location of a charge within the electric field
• Potential difference is the difference between two electric potential values, which is responsible for the generation of electric current
• Earth's potential is equal to 0
• Work is the influence of a rest charge over a moving charge moving within the rest charge's electric field
• Potential gradient is the local rate of change of a potential with respect to the displacement
• A capacitor, also known as a condenser, is an electric component that stores electrical energy within an electric field
• Capacitance refers to the ability of a capacitor to store charge, which will change the voltage of a body by one
• Stored energy is energy stored due to half the work performed
• Electric field energy refers to the energy of the electric field, which is equal to the electric field's energy density
• A dielectric is an insulating material inserted between a capacitor's parallel plates, which increases capacitance without compromising the capacitor's separation distance
• Equivalent capacitance is the total capacitance within sets of given capacitors
• Series circuit refers to connected devices in the system is in a single fashion, sharing charge values
• Parallel circuit refers to connected devices in the system is independent from each other, sharing voltage values
• A gaussian surface doesn’t enclose a charge, value of a charge is equal to 0
• Electric work is defined as the loss of potential energy in a test charge moving in an electric field
• Michael Faraday: the unit farad is named after him
• The Philippine Electrical Code (RA7920) provides an act for practice, licensure, and regulation of electrical engineers and electricians

Electricity and Circuits

• A shuttered socket is a device fitted with internal protective shutters to protect children from electrocution
• Fuses protect circuits from excessive current by melting if the current is high enough, opening the circuit, and stopping the current flow
• Circuit breakers protect circuits from current overload, functions similarly to fuses, but do not get destroyed, making this a long-term safety device
• Ground fault circuit interrupters are designed to detect a tiny mismatch in currents to prevent electrocution and are mandatory in bathrooms, kitchens, or anywhere else in the house where water may come in contact with an electric circuit
• An equipotential earth point/stud is a device installed alongside plug sockets to the equipotential earthing system, which ensures all equipment is grounded at the same low potential
• Three-pronged plugs are plugs with a round prong that serves as the ground outlet for the device, which connects to the ground wire of the building
• Electrolysis occurs when polarized ions causes ulceration on the affected area
• Burns are due to low-to-high powered voltages that can cause minor to serious injuries
• Muscle cramps are uncontrollable muscular twitching due to electrical over stimulation
• Ventricular fibrillation is the same as muscle cramps, but affects the heart
• Electric current is the amount of charge in a conductor per unit time
• Direct current has both constant voltage and direction and is primarily used in battery-operated devices
• Alternating current means current direction and magnitude changes in between two extreme values, periodically reverses direction, and used in daily living
• Conventional alternating current means current flows from positive terminal of the source towards the negative
• Electron current flows from the negative terminal of the source towards the positive
• Current density is the amount of current per unit of area
• Drift velocity is the net motion of charged particles in groups
• Resistance is the property of a material to resist current, measured in Ohms (Ω)
• Conductance is the inverse of resistance, which is the property of the material to conduct electric current, measured in siemens (S)
• Resistivity is a measure of a material’s electrical resistance
• Conductivity is the inverse of resistivity, which is the measure of a material’s conductance
• Ohm’s Law was developed by Georg Simon Ohm which states that current is proportional to voltage, and inversed with resistance
• A curve is a graph that shows the relationship between current and resistance
• An ohmic device is a device that demonstrates Ohm’s law, with constant resistance
• A non-ohmic device is a device that does not show Ohm’s law
• Power is the rate at which energy is transferred
• Electromotive force is the work done by the voltage source to the circuit, always constant; the “cause” of a voltage’s occurrence
• Internal resistance is the resistance of a power source
• Terminal potential difference is the output voltage of a source, when internal resistance is considered
• Electrical hazard is a condition concerning man and electrical equipment, which results to injuries and/or death
• Electric shock is the physiological injury caused by passing electric current
• A lichtenberg figure shows a tree-like pattern
• Electrocution is death due to electric shock
• Current Law: At any junction in an electrical circuit, the sum of currentsflowing into the junction is equal to the sum of the currents flowing out
• Voltage Law: The sum of voltages encountered in a complete traversal of anyloop of a circuit (or mesh) is zero
• An RC circuit is a circuit with a resistor and a capacitor, which filters signals

Magnetism

• A magnet is a material capable of interacting with other materials easily influenced by magnetism
• A magnetic pole is a region of a magnet that is polarized
• A magnetic field is a field of force surrounding a magnet
• Lorentz force is the force influenced by both electric and magnetic forces
• Cyclotron radius is the radius of charged particles circular motion
• Cyclotron frequency is the angular frequency of a charged particle’s circular motion
• Magnetic flux is a measure of a magnetic field strength per area, measured in Weber
• A solenoid is a conducting wire coiled in a helix, which functions similarly as arranged single-loop conductors
• Biot-Savart Law describes the magnetic field being generated by changing electric fields, being consistent with both Ampere’s and Gauss’s Laws
• Ampere’s Law relates current and magnetic field
• Electric force refers to when it is projected parallel from the electric field
• Magnetic force refers to when it is projected perpendicular from the magnetic and electric fields
• Current density is a particle which is not part of drift velocity