Current, potential difference, and resistance

• What is the purpose of a cell or battery in a circuit?

  Provides a source of potential difference
• What does a switch do in a circuit?

  Turns the circuit on or off
• How does a fixed resistor function in a circuit?

  Limits the flow of current with constant resistance
• What is the function of a variable resistor?

  Changes its resistance using a slider
• How does a thermistor's resistance change?

  Decreases as temperature increases
• What does an LDR do?

  Changes resistance based on light intensity
• What is the function of a diode?

  Allows current to flow in one direction only
• What is a light-emitting diode (LED)?

  Emits light when current passes through it
• What is the purpose of an ammeter?

  Measures the current in a circuit
• How is a voltmeter connected in a circuit?

  Connected in parallel with the component
• What is the significance of the resistance of an ammeter?

  Its resistance is negligible in calculations
• What is the role of a closed path in a circuit?

  Allows electrons to flow in a complete loop
• What happens when a switch is closed in a circuit?

  The circuit becomes complete and current flows
• How does the direction of current flow relate to electron flow?

  Current flows from positive to negative, opposite to electrons
• What is the unit of electric current?

  Amperes (A)
• What is the relationship between charge and current?

  Current is the rate of flow of charge
• How do you calculate work done moving charge through potential difference?

  Use the equation W = VQ
• What is the work done moving a charge of 5 C through 20 V?

  100 J
• What is the unit of charge?

  Coulomb (C)
• How is current defined in terms of charge?

  Charge passing a point per second
• What is the relationship between current and resistance?

  Higher resistance leads to lower current
• What is the symbol for resistance?

  R
• How is resistance measured?

  In Ohms (Ω)
• What does an increase in resistance do to current?

  Decreases the current for a given voltage
• How do you calculate potential difference across a resistor?

  Use the equation V = IR
• What is the potential difference across a resistor of 10 Ω with 0.3 A current?

  3 V
• What happens when an electron hits the lattice in a wire?

  It transfers energy and slows down
• Why does the wire heat up?

  Due to collisions of electrons with the lattice
• How does the temperature of the wire affect its resistance?

  Higher temperature increases resistance
• What is the formula for potential difference in terms of resistance and current?

  V = IR
• Calculate the potential difference through a resistor of resistance 10 Ω with a current of 0.3 A.


  3 V
• What are the variables in the resistance investigation experiment?

  • Independent variable: Length of resistance wire, L
  • Dependent variable: Resistance, R
  • Control variables:
  • Potential difference of the power supply
  • Temperature of the wire
• What is the resolution of a voltmeter in the resistance experiment?

  0.1 V
• What should be done after taking a reading in the resistance experiment?

  Disconnect the circuit immediately
• What does a straight line graph through the origin indicate in the resistance experiment?

  Resistance is directly proportional to length
• What is a confounding variable in the resistance experiment?

  A variable that impacts the results unexpectedly
• What is the effect of adding resistors in series on total resistance?

  Total resistance equals the sum of individual resistances
• How does the current flow through resistors in series?

  Through one path for all resistors
• What happens to the total resistance when resistors are connected in parallel?

  Total resistance is less than individual resistances
• What is Ohm's Law?

  Current is directly proportional to potential difference