CW

• What is electricity defined as in the study material?

  Electric force is the flow of electric force in a conductor.
• What are electrons in motion associated with?

  Electrons in motion are associated with charge and resistance generated via mechanical, thermal, chemical, magnetic methods, and conductivity.
• What is the unit of charge?

  The unit of charge is the coulomb.
• How many electrons are in one coulomb?

  One coulomb is equivalent to approximately \(6.24 \times 10^{18}\) electrons.
• What does the formula \(Q = I \cdot t\) represent?

  The formula \(Q = I \cdot t\) represents the total charge \(Q\) in coulombs, where \(I\) is the current in amperes and \(t\) is the time in seconds.
• How much charge is represented by 4600 electrons?

  The charge represented by 4600 electrons is approximately \(7.3779 \times 10^{-16}\) coulombs.
• What is the unit of current?

  The unit of current is the ampere (A).
• What is the formula for resistance?

  The formula for resistance is \(R = \frac{\rho L}{A}\), where \(\rho\) is resistivity, \(L\) is length, and \(A\) is area.
• How do you calculate the resistance of a 1.2 km copper cable with a diameter of 12 mm?

  The resistance can be calculated using the formula \(R = \frac{\rho L}{A}\) with \(\rho = 1.7 \times 10^{-8} \, \Omega \cdot m\), \(L = 1200 \, m\), and \(A = 1.13 \times 10^{-4} \, m^2\).
• What does Ohm's law state?


  Ohm's law states that \(V = IR\), where \(V\) is voltage, \(I\) is current, and \(R\) is resistance.
• What is electrical power usually expressed in?


  Electrical power is usually expressed in watts (W).
• What is the relationship between power, voltage, and current?

  The relationship is given by the formula \(P = VI\), where \(P\) is power, \(V\) is voltage, and \(I\) is current.
• How do you find the power delivered to an element at \(t = 3 \, ms\) if the current is \(i = 5 \cos(\omega t)\) and the voltage is \(v = 3i\)?


  The power delivered can be calculated using \(P = VI\) and substituting the values for \(i\) and \(v\) at \(t = 3 \, ms\).
• What is the formula for electrical energy?

  The formula for electrical energy is \(E = Pt\) or \(E = \int P \, dt\).
• How much energy does a heater consume if it is rated at 1000 watts and runs for 30 minutes?


  The energy consumed is \(E = Pt = 1000 \, W \cdot 1800 \, s = 1800000 \, J\) or 1.8 MJ.
• What is electric current defined as?

  Electric current is defined as the flow of electric force in a conductor.
• What are the required components for a current to flow in a circuit?


  The required components are a source of voltage, a closed loop of wiring, an electric load, and a means of opening or closing the circuit.
• What is the difference between direct current (DC) and alternating current (AC)?

  DC flows in one direction, while AC changes direction periodically.
• What is a common application of direct current (DC)?

  Common applications of DC include batteries and electronic equipment.
• What is a common application of alternating current (AC)?

  Common applications of AC include home and office outlets and power transmission over long distances.
• How is AC produced?

  AC is produced using an alternator.
• What is the role of transformers in AC power systems?

  Transformers are used to convert AC from high voltage to low voltage and vice versa.
• What are the advantages of using AC for power transmission?


  Advantages include less energy loss over long distances, easy conversion between high and low voltages, and lower heat generation in power lines.
• What are the factors that influence resistance in conductors?

  • Composition of the conductor
  • Length of the wire
  • Cross-sectional area
  • Temperature
• What are the symbols for different sources of voltage?

  • Single cell
  • Multiple cell
  • DC Voltage
  • AC Voltage
• What are the applications of solar panels?

  • Generating electricity
  • Producing direct current
  • Feeding into AC mains with an inverter
• What are the applications of electronic equipment that use DC?

  • Computers
  • Radios
  • Mobile phones
  • Integrated circuits
• What are the applications of AC in large appliances?

  • Refrigerators
  • Dishwashers
  • Electric motors