Physics

• What is the unit of electric current?


  Amperes (A)
• How is current defined?


  It is the rate of flow of electrical charge.
• What is the relationship between amperes and coulombs?


  1 ampere = 1 coulomb per second.
• What is the unit of potential difference?


  Volts (V)
• How is potential difference defined?


  It is the work done per unit of charge.
• What is the relationship between joules and coulombs in terms of potential difference?


  1 volt = 1 joule per coulomb.
• What is the unit of resistance?


  Ohms (Ω)
• How is resistance defined?


  It measures how difficult it is to get a current to flow through a component.
• What is the unit of power?

  Watts (W)
• How is power defined?


  It is the rate at which energy is transferred.
• What is the relationship between watts and joules?


  1 watt = 1 joule per second.
• What does Ohm's Law state?


  The current through a resistor is directly proportional to potential difference and inversely proportional to resistance.
• What is the formula for Ohm's Law?


  V = IR
• What are the characteristics of a series circuit?


  • Current is the same at all points.
  • Potential difference is shared across each component.
  • Total resistance is the sum of the resistances.
• What are the characteristics of a parallel circuit?


  • Potential difference across each branch is the same.
  • Current is divided between each branch.
  • Total resistance is less than the smallest resistor.
• What is the role of a step-up transformer?


  It increases the potential difference and reduces the current.
• What is the role of a step-down transformer?


  It decreases the potential difference and increases the current.
• What is the function of an LDR?


  • A resistor whose resistance depends on the intensity of light.
• What is the function of a thermistor?


  • A resistor whose resistance depends on temperature.
  • Generally, the higher the temperature, the lower the resistance.
• What does a diode do?


  It only allows current to flow in one direction.
• What are the key equations in G.C.E. for electricity?


  1. \( V = \frac{E}{Q} \)
  2. \( P = IV \)
  3. \( P = I^2R \)
  4. \( V = IR \)