Physics

• Charles-Augustin de Coulomb measured the force between two point charges
• Identify

  • F - Force - N
  • q - Quantity of charge - C
  • r - Distance - m
  • k - Coulomb’s Law Constant - N∙m^2/C^2
• Identify


  Symbol, Name, Unit
• Marginal utility is the additional utility (satisfaction) gained from the consumption of an additional product. Total utility is the sum of marginal utilities for each unit
• Coulomb found that the force is inversely proportional to the square of the distance between two charges and directly proportional to the product of charges
• Coulomb’s Law


  Gives an idea of the force between two charges, acts along the line joining the two charges considered to be point charges
• If q1 and q2 are doubled, then F is quadrupled
• Lesson 3: Coulomb’s Law between three charges
• The force (F) is directly proportional to the product of the charges
• The force (F) is inversely proportional to the square of the separation distance (r^2)
• Since we are finding the distance (r) between two charges, we need to derive our original formula
• If r is doubled, the F becomes 1/4 of the original value
• Calculating net force between charges

  Calculate the force between q1 and q2, then between q1 and q3
• Quantity of charges (q) is always absolute value
• Coulomb’s Law Constant (k) is always given
• If q1 is doubled, then F is doubled
• It means they attract

  Direction of the �3,1 is going left (←) and the sign of the force is negative
• It means they repel


  Direction of the ��,� is going left (→) and the sign of the force is positive
• It means they attract

  Direction of the ��,� is going left (←) and the sign of the force is negative
• Voltage describes the “pressure” that pushes electricity
• If the direction is left it means the force is negative and If the direction is right it means the force is positive
• Current is the rate at which electrons flow past a point in a complete electrical circuit. At its most basic, current = flow
• The direction of attract is left (←) and the direction of repel is right (→)
• Resistance is measured in Ohms, symbolized by the Greek letter Omega (Ω)
• Force is based on direction if it is attract or repel
• Ohms are named after Georg Simon Ohm (1784-1854), a German physicist who studied the relationship between voltage, current and resistance
• FC,A − qC is positive and qA is also positive


  They repel. Direction of the force is left (→) and the sign is positive
• The amount of voltage is indicated by a unit known as the volt (V), and higher voltages cause more electricity to flow to an electronic device. In brief, voltage = pressure
• Resistance is a measure of the opposition to current flow in an electrical circuit
• Ohm’s discovery revealed that “the amount of current flowing through a conducting material in a circuit is directly proportional to the potential difference across it”. This is mathematically expressed in a simple equation, as follows: V = IR
• FC,B − qC is positive and qB is negative


  They attract. Direction of the force is left (←) and the sign is negative
• Conductors


  • Materials that offer very little resistance where electrons can move easily
  • Examples: silver, copper, gold and aluminum
• Insulators


  • Materials that present high resistance and restrict the flow of electrons
  • Examples: Rubber, paper, glass, wood and plastic
• An ampere (A), or amp, is the international unit used for measuring current
• Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms
• The common symbol for current is the uppercase letter I
• Power equation

  P = VI (where P is power, V is voltage, and I is current)
• Power


  Power dissipates from the resistance as current passes through it, measured in watts (W)
• Example 1 solution

  I = V/R = 100V / 10 Ohms = 10A
• Ohm's Law equation


  V = IR (where V is voltage, I is current, and R is resistance)