2.1 Current, Potential Difference & Resistance

• What are circuit diagrams used for?

  To represent electrical circuits visually
• What is the function of a cell or battery in a circuit?

  Provides a source of potential difference
• How does a switch function in a circuit?

  Turns the circuit on (closed) or off (open)
• What is the role of a fixed resistor?

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

  To change its resistance using a slider
• How does a thermistor behave with temperature changes?

  Resistance decreases as temperature increases

  
• What does an LDR do in response to light intensity?

  Resistance decreases as light intensity increases
• What is the function of a diode in a circuit?

  Allows current to flow in one direction only

  
• What is a light-emitting diode (LED)?

  A diode that emits light when current flows
• 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 negligible resistance in ammeters and voltmeters?

  They do not significantly affect circuit current
• What are the essential components of an effective electric circuit diagram?

  • An energy source (cell, battery, power supply)
  • A closed path or complete circuit
  • Electrical components (sensors, measuring devices, energy transfer devices)

  
• What is the direction of current flow in a circuit?

  From positive to negative terminal
• What must be true for a circuit to be connected?

  The switch must be closed
• What does a forward-biased diode do?

  Allows current to flow in one direction
• What is the symbol for potential difference?

  V

  
• How is potential difference defined?

  Energy transferred per unit charge flowing
• What is the unit of potential difference?

  Volts (V)

  
• How much energy does a bulb with 3 V lose per coulomb?

  3 J of energy
• How is potential difference measured?

  Using a voltmeter in parallel
• What is the work done moving a charge of 5 C through 20 V?

  100 J
• What is electric current?

  Flow of electrical charge
• What is the unit of electric current?

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

  Charge is the quantity of electrons flowing

  
• How is one coulomb defined?

  Charge passing a point with 1 A current
• What is the equation relating charge, current, and time?

  Q = It

  
• How do you calculate current if 4 C passes in 500 s?

  Using Q = It
• What is conventional current?

  Flow of positive charge from positive to negative

  
• How is current measured in a circuit?

  Using an ammeter connected in series

  
• What happens to current in a closed-loop circuit?

  Current is the same at each point
• What is resistance?

  Opposition to current flow in a circuit
• What is the unit of resistance?

  Ohms (Ω)
• How is resistance defined in terms of voltage and current?

  1 V per A (1 V/A)
• How does resistance affect current?

  Higher resistance means lower current
• What is the relationship between current, resistance, and potential difference?

  • Current (I) depends on resistance (R) and potential difference (V)
  • Higher resistance results in lower current
  • Lower resistance results in higher current

  
• How can resistance be increased in a circuit?

  By adding resistors or variable resistors
• How do you calculate potential difference across a resistor?

  Using V = IR

  
• What is the potential difference across a 10 Ω resistor with 0.3 A current?

  3 V
• What happens to the lattice when it gains energy?

  It vibrates more with each collision