Physics: Magnetism and Electricity

Magnetism

Magnetic Fields

• A magnetic field is a region around a magnet or electrical current where the magnetic force can be detected
• Magnetic fields are created by the motion of charged particles, such as electrons
• The direction of a magnetic field is defined by the direction of the force it would exert on a test charge

Magnetic Poles

• Every magnet has two poles, the north pole and the south pole
• Like poles (north-north or south-south) repel each other, while opposite poles (north-south) attract each other
• The strength of a magnet is determined by the distance between its poles and the material it is made of

Magnetic Forces

• The force exerted by a magnetic field on a moving charge is given by the Lorentz force equation: F = qv x B
• The force exerted by a magnetic field on a current-carrying wire is given by the equation: F = IL x B
• Magnetic forces can be attractive or repulsive, depending on the direction of the magnetic field and the moving charge or current

Electricity

Electric Charge

• Electric charge is a fundamental property of matter that can be positive or negative
• Positive charge is associated with protons, while negative charge is associated with electrons
• Electric charge is quantized, meaning it comes in discrete amounts (e.g., 1 electron has a charge of -1.6 x 10^-19 C)

Electric Field

• An electric field is a region around a charged object where the electric force can be detected
• The electric field is a vector field that points away from positive charges and towards negative charges
• The strength of an electric field is measured in units of volts per meter (V/m)

Electric Potential

• Electric potential, or voltage, is the potential energy per unit charge at a given point in an electric field
• The electric potential difference between two points is measured in volts (V)
• Electric potential is a scalar quantity, meaning it has no direction

Electric Circuits

• An electric circuit is a path through which electric current flows
• Electric circuits consist of sources of electromotive force (EMF), resistors, capacitors, and inductors
• Kirchhoff's laws are used to analyze and design electric circuits:
  • Kirchhoff's Voltage Law (KVL): The sum of the voltage changes around any closed loop is zero
  • Kirchhoff's Current Law (KCL): The sum of the currents entering a node is equal to the sum of the currents leaving a node