LAST NA TO PHYSICS!!!!!!

CURRENT, RESISTANCE, VOLTAGE, AND OHM’S LAW

CURRENT

• amount of charge flowing on a wire at a certain area per unit time. 

• Movement of particles are affected by the ELECTRIC FIELD

• Coulomb per sec or AMPERE (A) 

CURRENT FLOW

1. CONVENTIONAL CURRENT

• Current flows from positive back to the negative side

2. ELECTRON FLOW

• From NEGATIVE to POSITIVE

TYPES OF ELECTRIC CURRENT

1. DIRECT CURRENT (DC)

• FLOWS IN ONE DIRECTION

2. ALTERNATING CURRENT (AC)

• CHANGES DIRECTION PERIODICALLY

RESISTANCE

•  opposition of the material to the flow of charge carriers.

•  resistance to the flow of charge

•  VOLT PER AMPERE OR OHM

RESISTOR 

• device that contributes appreciable resistance to the flow of charge.

VOLTAGE 

• Potential difference

• required energy to move the unit charge from one point to other

• VOLTS

ELECTROMOTIVE FORCE (EMF)

• It is the energy supply to the charge BY A BATTERY CELL. EMF is the maximum potential difference between two terminals of a battery when no current is flowing from the source.

OHM’S LAW

• GEORG SIMON OHM 

• 1827

•  current in a circuit is directly proportional to the electric pressure and inversely to the resistance of the conductors

•  direct proportionality between current and voltage but inversely proportionality between current and resistance

ELECTRIC WORK

•  amount of energy required to transfer a charge through a potential difference.

• JOULE 

ELECTRIC POWER

• rate at which energy is delivered by a source as it carries charge through a potential rise in a time.

• How fast energy is delivered/used

• WATT

PHYSIOLOGICAL EFFECTS OF CURRENT

1. Standard voltage of outlets in phil is 220V

2. Plugging 110V to 220 V? In most appliances, It will develop more heat and probably burns out in minutes

3.  Plugging 220 V to 110 V?  It will normally last longer before it dies or in some instances, will fail to start 

\

RESISTORS IN CIRCUITS

RESISTORS IN SERIES 

• WHEN CURRENT CAN FLOW ONLY ONE PATH AS IT FOLLOWS THROUGH TWO OR MORE RESISTORS CONNECTED IN LINE

RESISTORS IN PARALLEL

• SEVERAL RESISTORS ARE CONNECTED IN PARALLEL BETWEEN NODES IF ONE END OF EACH RESISTOR IS CONNECTED TO ONE NODE AND THE OTHER END OF EACH IS CONNECTED TO OTHER NODE.

• THE TOTAL RESISTANCE IN PARALLEL IS ALWAYS LESS THAN THE SMALLEST RESISTOR

SERIES TO PARALLEL:

PARALLEL TO SERIES: 

Here are all the terms and their definitions exactly as stated in the provided file:

MAGNET

• Has two magnetic poles: North Pole (N) and South Pole (S).
  
  

• Each magnet has its own magnetic field.
  
  

MAGNETIC FIELD

• Made up of imaginary field lines, similar to electric fields, which describes magnetic force in a given region.
  
  

• The field lines form loops inside the magnet.
  
  

MAGNETIC INTERACTION

• In magnets, like poles repel and opposite poles attract, just like the electric charges, however, charges can be isolated.
  
  

• If you cut a magnet into two pieces, each piece will still have two poles.
  
  

COMPASS

• A magnetic field is detected by its effect on a compass’ magnetic needle.
  
  

• Compass needle is always pointing to the north.
  
  

EARTH’S MAGNETIC FIELD

• Due to large amount of magnetized material on the core, Earth’s magnetic field is immense, expanding to the outer space called the magnetosphere.
  
  

• This magnetic field protects Earth from harmful particles coming from the sun (called the solar wind).
  
  

• Northern Lights (Aurora Borealis) and Southern Lights (Aurora Australis)
  
  

MAGNETIC DOMAINS

• Magnet is actually made up of tiny regions called magnetic domains, typically 1 square millimeter in area.
  
  

• Each domain has their own set of poles.
  
  

• The presence of magnetic field in ferrous materials affects the domain as it lines up with the field.
  
  

KINDS OF MAGNETS

• Permanent Magnets
  
  

• Temporary Magnets
  
  

• Electromagnets
  
  

PERMANENT MAGNETS

• A kind of magnet where objects remains attracted even removed from the other magnetic field of another object.
  
  

TEMPORARY MAGNETS

• A kind of magnet where objects will repel once removed from the other magnetic field of another object.
  
  

ELECTROMAGNETS

• Magnets can be useful if there’s a presence of electric current.
  
  

NON-MAGNETIC MATERIALS

• If materials are not magnetized in the presence of electric field and domains cancel out each other, they are called to be non-magnetic.
  
  

• Wood, plastic, glass, etc.
  
  

CONNECTION OF ELECTRICITY AND MAGNETISM

• An electric current produces a magnetic field.
  
  

• When current runs through an electric wire, the magnetic field circles around the wire.
  
  

• Electricity and magnetism are essentially two aspects of the same thing, because a changing electric field creates a magnetic field, and a changing magnetic field creates an electric field.
  
  

FIRST RIGHT HAND RULE

• The thumb of the right hand points to the North Pole of the solenoid when the hand is wrapped in the same way as the electric current around the solenoid. The fingers point in the conventional direction of the electric current.
  
  

MAGNETIC FIELD STRENGTH (B)

• The strength of magnetic field can be measured whenever there is a current flowing on a wire.
  
  

• Unit: Tesla (T)
  
  

SOLENOID

• An electromagnet that generates a controlled magnetic field through a coil wound into tightly packed helix.
  
  

MAGNETIC FLUX

• Magnetic flux is the measure of the total magnetic field that passes through an identified area perpendicular to the magnetic field.
  
  

• Instrument: Magnetometer
  
  

• SI unit: Weber (Wb)
  𝜙 = 𝐵𝐴
  
  

MAGNETIC FORCE

• The magnetic field exerts a force on a current-carrying wire in a direction.
  
  

• This force can easily be large enough to move the wire, since typical currents consist of very large numbers of moving charges.
  
  

• SI unit: Newton (N)
  𝐹 = 𝐼𝐿𝐵 sin 𝜃
  
  

SECOND RIGHT HAND RULE

• If you point your pointer finger in the direction the positive charge is moving, and then your middle finger in the direction of the magnetic field, your thumb points in the direction of the magnetic force pushing on the moving charge.
  
  

AMPERE’S LAW

• “The magnetic field created by an electric current is proportional to the size of that electric current with a constant of proportionality equal to the permeability of free space.”
  𝐵 = 𝜇𝑂𝐼
  
  

ELECTROMAGNETIC INDUCTION

• It is the production of an electromotive force across an electrical conductor in a changing magnetic field.
  
  

• It also causes the change in magnetic flux.
  
  

ELECTROMOTIVE FORCE

• Electromotive force is not a force, it is the potential difference or the potential energy per charge.
  
  

• It is what causes the electron to move and form the current.
  
  

FARADAY’S LAW

• “The induced emf in a closed loop is equal to the negative of the time rate of change of the magnetic flux through the loop.”
  𝜀 = −𝑑𝜙𝐵/𝑑𝑡
  𝜀 = −𝑁𝑑𝜙𝐵/𝑑𝑡
  
  

LENZ’S LAW

• “An induced current that induces a counter magnetic field opposes the magnetic field generating a current.”
  
  

ELECTRIC MOTOR

• Electric motor transforms electrical energy to mechanical energy.
  
  

MOTOR

• A motor consists of loops of wire in a magnetic field. When current passes through the loops, the magnetic field exerts a torque on the loops and converts the electrical energy to mechanical energy, that makes the rotation of the loops of wire.
  
  

KINDS OF ELECTRIC MOTOR

• DC Motors: used cells and battery to power up the motor and permanent magnets.
  Common in: toys, remote-control cars, small fans
  
  

• AC Motors: used main electricity lines and electromagnets rather than permanent magnets.
  Common in: home appliances (fans, washing machines, fridges), industrial machines
  
  

GENERATOR

• Generator transforms mechanical energy to electrical energy.
  
  

GENERATOR (Mechanism)

• The generator consists of loops of wire wrapped around an iron core (solenoid) and placed in a magnetic field. The armature is mounted on the wire, so it can rotate in the magnetic field.
  
  

• As the armature spins using up mechanical energy, the loops of wire cut across the field and produce electric current (induction). The produced current of a generator is called alternating current.
  
  

BACK-EMF

• Back electromotive force is the voltage generated during the operation of a rotating machine (a generator or a motor).

TRANSFORMER

• Transformer is a device that helps transfer electrical energy through electromagnetic induction.
  
  

• Transformer has two coils: a primary coil and a secondary coil.
  
  

• When the primary coil is connected to an AC voltage, the changing current creates a varying magnetic field, which induces a varying EMF in the second coil.
  
  

KINDS OF TRANSFORMER

• Step-up Transformer: The secondary voltage is larger than the primary voltage.
  
  

• Step-down Transformer: The secondary voltage is smaller than primary voltage.
  
  

FORMULAS: 

📘 Magnetism & Electromagnetism  Formula List

1. Magnetic Flux
   Formula: φ = B × A
   Where:
   
   

   • φ = Magnetic flux (Weber, Wb)
     
     

   • B = Magnetic field strength (Tesla, T)
     
     

   • A = Area perpendicular to field (m²)
     
     

2. Magnetic Force on a Current-Carrying Wire
   Formula: F = I × L × B × sin(θ)
   Where:
   
   

   • F = Magnetic force (Newton, N)
     
     

   • I = Current (Amperes, A)
     
     

   • L = Length of wire in field (m)
     
     

   • B = Magnetic field (Tesla, T)
     
     

   • θ = Angle between wire and magnetic field

3. Ampere’s Law (Simplified Form)
   Formula: B = μ₀ × I
   Where:
   
   

   • B = Magnetic field (Tesla, T)
     
     

   • μ₀ = Permeability of free space ((1.257 × 10−6 Tm/A)
     
     

   • I = Current (Amperes, A)
     
     

4. Faraday’s Law of Electromagnetic Induction (Basic Form)
   Formula: ε = -dφ/dt
   Where:
   
   

   • ε = Induced EMF (Volts, V)
     
     

   • dφ/dt = Rate of change of magnetic flux (Wb/s)

5. Faraday’s Law (With Multiple Turns)
   Formula: ε = -N × dφ/dt
   Where:
   
   

   • N = Number of turns in the coil
     
     

6. Magnetic Field Around a Long Straight Wire
   Formula: B = (μ₀ × I) / (2π × r)
   Where:
   
   

   • r = Distance from wire (meters)
     
     

7. Magnetic Field at the Center of a Circular Loop
   Formula: B = (μ₀ × I) / (2 × r)
   Where
   
   

   • r = Radius of the loop (meters)

8. Magnetic Field Inside a Solenoid
   Formula: B = μ₀ × n × I
   Where:
   
   

   • n = Number of turns per unit length (N/L)
     
     

9. Magnetic Force on a Moving Charge
   Formula: F = q × v × B × sin(θ)
   Where:
   
   

   • F = Force (N)
     
     

   • q = Charge (Coulombs, C)
     
     

   • v = Velocity (m/s)
     
     

   • B = Magnetic field (T)
     
     

   • θ = Angle between velocity and field