physics topic 2

• What is electricity defined as?

  The flow of charge or charges
• What do electrons carry in an electrical circuit?

  Energy from a source to a component
• What is a simple circuit composed of?

  • A cell (or battery)
  • Wires
  • A lamp (light bulb)
• What is the symbol for a battery?

  Several cells connected in line
• Why must circuits have complete loops?

  To allow charges to flow continuously
• What type of energy does a battery store?

  Chemical potential energy
• What happens to electrons when connected in a complete circuit?

  They move through the wires carrying energy
• What is the term for the movement of charge in a circuit?

  Current
• From which terminal do electrons flow in a battery?

  From the positive terminal to the negative
• What is the energy conversion that occurs as electrons pass through a bulb?

  Energy is converted into light and heat
• What happens to electrons after they transfer energy to the bulb?

  They are pushed back to the battery
• What do we measure charge in?

  Coulombs
• What does potential difference (PD) indicate?

  Energy transferred per coulomb of electrons
• What does a 1-volt battery supply?

  One joule per coulomb of electrons
• How is PD measured in a circuit?

  With a voltmeter connected in parallel
• What should a voltmeter read when placed across a battery?

  It should measure the battery's voltage
• What does a voltmeter read when placed across a bulb?

  It should still read the battery's voltage
• What is the equation for potential difference (PD)?

  PD = energy / charge
• What is the symbol for charge?

  Q
• What does current measure?

  The rate of flow of charges
• What is the equation for current?

  I = Q / T
• What is the unit for current?

  Amps
• How is current measured in a circuit?

  With an ammeter connected in series
• What is resistance in a circuit?

  • Resistance resists the flow of charge
  • Necessary for components to function
  • Causes energy transfer in bulbs and resistors
• What happens to current when PD increases in a resistor?

  Current increases proportionally
• What does a straight line graph of PD versus current indicate?

  It indicates constant resistance (ohmic)
• What is Ohm's Law equation?

  V = IR
• How can resistance be calculated from a graph?

  Using Ohm's Law: R = V / I
• What happens to resistance in a filament bulb as PD increases?

  Resistance changes and increases
• Why does resistance change in metals?

  Due to collisions with vibrating ions
• What is a diode's function in a circuit?

  Allows current to flow in one direction
• What is an LED?

  A light-emitting diode
• What is the relationship between wire length and resistance?

  • Resistance increases with wire length
  • Measured using Ohm's Law
  • Demonstrated through a straight line graph
• What are the rules for series circuits?

  • Total PD is shared among components
  • Current is the same through all components
  • Total resistance is the sum of all resistances
• What happens to PD in series circuits with equal resistors?

  PD is shared equally among them
• How does current behave in series circuits?

  Current remains the same for all components
• What is the rule for total resistance in series circuits?

  Total resistance is the sum of resistances
• What are the rules for parallel circuits?

  • PD is the same across all branches
  • Current is shared between branches
  • Total resistance decreases with more resistors
• What is the PD across each branch in a parallel circuit?

  It is the same for every branch
• How does current behave in parallel circuits?

  Current is shared among branches