L1 [PT 8] Midterm Reviewer PDF

Electrotherapy Notes Electrodes Lesson 1. Physics of Electricity 1. Anode Shean Emmanuel Porcia – Anion is attracted to; unlike charges (Positive=N...

Electrotherapy Notes Electrodes Lesson 1. Physics of Electricity 1. Anode Shean Emmanuel Porcia – Anion is attracted to; unlike charges (Positive=Negative) attract each Atom – Minute indivisible particle that other (Anode is (+) electrode while comprise all matter Anion is (-) ions) - Universal color is Red An atom consists of an: (Hint: Anode=Anion) 1. Nucleus – central part of the atom; it is 2. Cathode composed of: - Cation is attracted to; unlike a. Proton (P=Positive charged) – it charges (Positive=Negative) determines the atomic number attract each other (Cathode is of the atom (-) electrode while Cation is (+) b. Neutron (Neu=Neutrally ions) charged) – have equal number - Universal color is Black of protons and affects the (Hint: Cathode=Cation) atomic mass (weight) - Both PROTON and NEUTRON Electricity cannot be removed from the - Form of energy; there is flow of nucleus electric charge 2. Electrons (Negatively Charged) - A Charged Body continues to - revolves in orbits around the attain neutrality. nucleus o If Negative charged it - Arranged in definite shells or would lose electrons orbits (Quantum Shell) o if Positive charged it - Can be removed from the would gain electrons. Nucleus (Can be gained or lost) o This process creates an Electric Field which is made up of lines of force - The properties of lines of force are: lines of force are straight lines of force pass more easily through conductors than through insulators lines of force concentrate nearest to another object over Neutral Atom – Equal number of protons and which they can exert an electrons influence Cation (+) ions Anion (-) ions lines of force travel Loss of electrons in gain of electrons in from negative to the atom leading to the atom leading to positive excess of protons -> excess of electrons -> Positive charge negative charge Conductors o capacitance of the object - materials which can transmit electrical current Quantity of electricity - atoms have few electrons in - Measured in Coulomb their outermost orbits since o 1 Coulomb (C) = 6.26 x they are few, they are loosely 1018 electrons charges held so that it will drift away - The higher or bigger the from the atom, facilitating the quantity of electricity passage of electron current. (Coulombs) the higher the - They are mostly metals such as Electrical Potential is. (Directly iron, copper, and the human Proportional) tissue as an exception - If you have 2 objects charged with different quantities of Non-conductors/Insulators electricity, the one with greater - Will not transmit electrical quantity of electricity has a charges/current greater power so it has greater - Atoms are firmly held and it potential of the two. will not leave the atom Capacitance - They are non-metal objects - The ability of the object to hold such as rubber, sand, and etc. an electrical charge - The capacitance of the object Electrical Charge depends on: - Occurs when the atoms have o Material – conductors Unequal numbers of electrons (metals, human skin) and protons. have greater power of o If more protons (fewer storing a charge and electrons) then it is tends to have a large more positively capacity charged. o Surface area – the o If more Electrons (Less greater, the greater the Protons) then it is more capacity negatively charged. - Inversely proportional to - As mentioned earlier, Matter electrical potential; If the with the same charge repel, but capacitance is high, the less the matter with different charges ability to move the charge attract - Unit is Farad (F) Electrical Potential Potential Difference - It is a force that causes a - There exists a difference of movement of charge to some potential in objects having distance is called Potential charges with different - Unit is Volt (V) quantities of electricity - The magnitude or how strong - If they have different quantities the potential is depends on: of electricity therefore their o quantity of electricity potential is different with which the object is (Difference of the potential). If charged there is potential difference, the electrons will flow to the  direction of negative to positive (Electron Flow). - Force producing the movement is the Electromotive Force (EMF) wherein it is measured in Volts (V). - The greater potential difference the greater the EMF (Directly - intensity or magnitude of how Proportional) strong current is the rate of - Example: flow of electrons through the (A)5V & 3V vs. (B)4V & 3V conductor per second; measured in Ampere (A) (A)Has a greater potential difference therefore Ohm’s Law it would have greater EMF compared to (B) - The magnitude or intensity(I) of the electric current varies - Electrons flow continues until directly with the EMF(E/V) and the potential of both objects inversely with the Resistance(R) are the same (If they become - EMF is directly proportional to equal = the flow of electrons the intensity. High EMF → there would stop are more number of electrons Electrical Current being moved (resulting to high - occurs when there is a flow of intensity) charged particles (generally electrons) in a conductor - Produced if there is: o a difference of potential (PD) o A conducting pathway between the points of potential difference - Some examples that can produce potential difference: o Electromagnetic Induction o Battery ▪ it has a positive and negative side (charges) ▪ It has difference in potential since Resistance one is more (+) - It opposes the flow of electrons and the other through the conductor more (-), - If a device that provides current will resistance to the flow is known flow in the as Resistor pathway - Unit Ohms (Ω)  - Electrical resistance depends on o The total resistance is the ff: less than any one of the o Material of the individual resistances 1 1 1 1 conductor o 𝑅𝑡𝑜𝑡𝑎𝑙 = 𝑅1 + 𝑅2 + 𝑅3 +⋯ ▪ Good conductor/mat erial = Less Resistance o Length of the pathway ▪ Longer the pathway = greater resistance o Cross sectional area of - When a current passes through the conductor a conductor, a portion of the ▪ Greater cross energy is converted to Thermal sectional (the Energy. more room the - Joule’s Law states that “the electrons to amount of heat produced in a pass) = conductor is proportional to the resistance square of the intensity of the lower current, the resistance and the ▪ Bigger wire time at which the current flows diameter = o Q = I2RT ; Unit is Joules lower (J) resistance ▪ Q = Heat ▪ Smaller ▪ I2 = square of diameter = intensity greater ▪ R = Resistance resistance ▪ T = Time (Easily - Greater Intensity of current Damaged or flow = more heat is produced Broken) - More resistance of current = o Temperature more heat is produced ▪ higher - Longer time = more heat is temperature produced (more Electrical Energy molecular - It is the ability of an electrical movement) = circuit to produce work by increases the creating action resistance - It supplies the power required Resistance Circuit to produce work or an action - Resistance in Series within an electrical circuit o Total resistance is equal Work to the sum of the - Dependent on the EMF and individual resistances quantity of electrons (Coulomb) o 𝑅𝑇𝑜𝑡𝑎𝑙 = 𝑅1 + 𝑅2 + 𝑅3 + ⋯ moved; Unit is Joules (J) - Resistance in Parallel o W = EMF x C  o High EMF = High Work - Observed that when a compass or Electrical Energy is brought near a conductor o More electrons moved with current, the needle of = High work or compass gets deflected because Electrical Energy of flow of electricity (Naay Power magnetic effect) - Rate of doing work; product of - Or when an electric current is EMF and intensity of current; applied to the coil of wire Unit is Watt (W) wound onto a soft iron bar, the - 1 Watt would indicate that an iron bar will be magnetized EMF of 1 volt moves 1 coulomb until the current is switch off of electrons (6.26 × 1018 ) in 1 Electromagnetic Induction sec. - electricity is produced from o P = EMF x I Magnetism - Result of interaction between a conductor and magnetic lines of force; EMF is produced by the magnetic lines of force - Factors of electromagnetic Current Flow induction: Conventional Current Flow - Magnetic lines of force is o Flows from positive to negative providing the electromotive Electron Flow force (No potential difference o Flows from negative to passive here) o Conductor There is the flow of the current o Magnetic lines of force o Relative movement of Magnetic Effect of an Electric Current conductor o Magnetic lines of force Ammeter – measures the ampere or the intensity/magnitude of the current When a magnet is moved into the coil, the magnetic lines of force cut across the conducting wire of the coil and cause movement of electrons in the coil, these electrons repel adjacent electrons and so on so that current is set up in the circuit - Also known as Electromagnetic Effect It also shows in electromagnetic induction that the magnet produces current  Death The current produced by electromagnetic induction is greater when the: Note: Always be careful when applying electrical magnet or coil moves faster, current modality the coil has more turns, or the magnet is stronger. If the magnet or coil is moved back and forth repeatedly, alternating current is produced Electric generators and electric transformers use electromagnetic induction to generate electricity or change the voltage of electric current THERAPEUTIC EFFECTS OF ELECTRICAL CURRENT : ▪ Facilitation of muscle contraction ▪ The current can stimulate the muscle to contract ▪ Enhance functional mobility ▪ Since it produces muscle contraction, then the patient can move that certain part ▪ Pain relief ▪ Resolve edema ▪ There is more muscle contraction, more mobility, therefore it can facilitate movement of fluid back to circulation ▪ Transport of medications ▪ Also found in Ultrasound through (Phonophoresis) ▪ Here electrical current can transport medication through (Iontophoresis) ▪ Wound healing ▪ Very rare to encounter in a rehab setting ADVERSE EFFECTS OF ELECTRICAL CURRENT Burns Encountered when exposed to high intensity current Chemical reactions Can be experienced after applying the modality Electrical Shock Earth Shock