electric circuits

• What are circuit symbols used for?


  To represent circuit components in circuit diagrams
• What are the types of circuit components mentioned in the notes?

  • Power supplies (cells, batteries, generators)
  • Resistors (fixed, variable, thermistors, LDRs)
  • Meters (ammeters, voltmeters)
  • Switches and functional components (motors, lamps, heaters, bells)
  • Electromagnetic components (magnetising coils, relays, transformers)
  • Fuses
• What do power supplies do in a circuit?


  They supply current to the circuit
• How do resistors function in a circuit?


  They control the current flowing through the circuit
• How are ammeters connected in a circuit?


  Ammeters are always connected in series
• How are voltmeters connected in a circuit?


  Voltmeters are always connected in parallel
• What is the role of switches in a circuit?


  They open and close a circuit to control current flow
• What are the specific roles of functional components in a circuit?

  • Motors rotate
  • Lamps emit light
  • Heaters transfer thermal energy
  • Bells emit sound
• What do electromagnetic components do in a circuit?


  They use electromagnetic effects to perform functions
• How do relays function in a circuit?


  They use a small current to switch on a larger current in another circuit
• What is the purpose of fuses in a circuit?


  To protect components from current surges and prevent fire
• What is a thermistor?


  A thermistor is a temperature-dependent resistor
• How does the resistance of a thermistor change with temperature?

  Resistance decreases as temperature increases
• What is a light-dependent resistor (LDR)?


  An LDR is a sensory resistor that changes resistance based on light energy
• How does the resistance of an LDR change with light intensity?


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


  A diode allows current to flow in only one direction
• What happens to current when a diode is flipped?


  It prevents current from flowing in the circuit
• What is a series circuit?


  A series circuit contains a single complete loop
• What is true about current in a series circuit?


  The current is the same value at any point in the circuit
• What factors affect current in a series circuit?

  The voltage of the power source and the resistance of the components
• What happens when the voltage of the power source is increased in a series circuit?


  More current flows around the circuit
• What happens when the number of components in a series circuit increases?


  Total resistance increases, leading to less current flow
• What is a parallel circuit?


  A parallel circuit consists of multiple loops containing circuit components
• What happens to current at a junction in a parallel circuit?


  The current splits along each branch
• Why are lighting circuits constructed in parallel?


  To ensure bulbs have the same brightness and continue functioning if one breaks
• What is the current conservation rule at a junction in a parallel circuit?


  The current flowing into the junction equals the current flowing out
• What does it mean that current does not always split equally in a parallel circuit?


  More current may flow in some branches than in others
• Why does current behave this way in a circuit?


  Because electrons are physical matter that cannot be created or destroyed
• What happens to the combined e.m.f. when cells are connected in series?


  It equals the sum of their individual e.m.f.s
• What is the relationship between potential differences in a series circuit?


  The sum of potential differences equals the total e.m.f. of the power supply
• What is the potential difference across each branch of a parallel circuit?


  It is the same as the e.m.f. of the power source
• How is the potential difference split in a branch with multiple components in a parallel circuit?


  The potential difference is split between the components on that branch
• What happens to the combined resistance when resistors are connected in series?


  The combined resistance equals the sum of individual resistances
• What happens to the combined resistance when resistors are connected in parallel?


  The combined resistance is less than the resistance of any individual component
• What is the combined resistance of two equal resistors connected in parallel?


  It will halve the resistance value of each resistor
• How do you determine the combined resistance of two resistors in parallel?


  Use the equation: $\frac{1}{R} =$$\frac{1}{R_1} +$$\frac{1}{R_2}$
• What is the method to calculate the resistance in parallel?


  First find the value of $\frac{1}{R}$ and then use the reciprocal function on your calculator
• What is a potential divider in a circuit?


  • A circuit that splits potential difference from a power source
  • The potential difference across each resistor depends on its resistance
  • The resistor with the largest resistance has a greater potential difference
  • If one resistor is variable, it can alter the potential difference across the other resistor
• How does the potential difference split between two resistors in series?


  • The potential difference splits in the same ratio as the resistance of the two resistors
  • The larger the resistance, the greater the potential difference across it