5.1 Current electricity

• Electric current is the flow of electric charge through a material.
• In Ohm's Law, voltage is directly proportional to both current and resistance.
• What is the relationship between resistance and cross-sectional area?

  Inversely proportional
• What is the unit of electrical resistance?

  Ohms (Ω)
• What is the effect of doubling the length of a material on its resistance?

  Doubles the resistance
• Conductivity is the reciprocal of resistivity.


  True
• The formula for power using voltage and current is $P =$$VI$
• What is the unit of electric current?

  Amperes (A)
• Match the Ohm's Law formula with its purpose:

  $V =$$IR$ ↔️ Calculates voltage

  $I =$$V / R$ ↔️ Calculates current

  $R =$$V / I$ ↔️ Calculates resistance
• Power is directly proportional to voltage and current.
• What unit is power measured in?

  Watts (W)
• What are the variables in the formula $P =$$I^{2}R$?


  $I$ = Current, $R$ = Resistance
• Match the electrical component with its description:

  Battery ↔️ Supplies electrical energy

  Resistor ↔️ Opposes current flow

  Lamp ↔️ Converts electrical energy to light

  Switch ↔️ Controls circuit flow

  Voltmeter ↔️ Measures voltage

  Ammeter ↔️ Measures current
• In a parallel circuit, components are connected across multiple paths.


  True
• Order the following applications of current electricity by their energy transformation:

  1️⃣ Lighting: Electrical → Light

  2️⃣ Heating Appliances: Electrical → Heat

  3️⃣ Electric Motors: Electrical → Mechanical

  4️⃣ Electronics: Electrical → Light, Sound, etc.

  5️⃣ Telecommunications: Electrical → Signals
• What is the primary assumption of conventional current?

  Flow from positive to negative
• What is the formula for current according to Ohm's Law?

  $I =$$V / R$
• The formula for resistance is $R =$$\rho \frac{L}{A}$, where <tex>$\rho$</tex> represents resistivity.
• The effect of material on resistance depends on its resistivity
• What is the effect of doubling the cross-sectional area of a material on its resistance?

  Halves the resistance
• What does electrical resistance oppose in a material?

  Flow of electric current
• What is the formula for power using current and resistance?

  P = I^{2} R</latex>
• In conventional current, the direction of flow is from positive to negative.
• For most metals, resistance increases with temperature.


  True
• The formula P = I^{2} R</latex> shows that power is directly proportional to the square of current.


  True
• Power represents the amount of energy delivered per unit time
• Power is inversely proportional to resistance
• In a series circuit, components are connected in a single path
• What happens to the current in a parallel circuit?

  It divides across branches
• An electric heater uses a resistor to convert electrical energy into heat.


  True
• What is electric current measured in?

  Amperes
• Electron flow describes the actual movement of negatively charged electrons from negative to positive.


  True
• Resistance increases with temperature in most metals.

  True
• Conductivity is the reciprocal of resistivity.


  True
• The resistance of most metals increases with temperature.


  True
• The formula for resistance is $R =$$\rho \frac{L}{A}$
• What is the unit of power in electrical circuits?

  Watts (W)
• Ohm's Law states that $V =$$IR$.


  True
• Electron flow describes the actual movement of electrons from negative to positive.

  True
• How does doubling the length of a material affect its resistance?

  Doubles the resistance