Electricity

• What is electricity defined as?

  Electricity is the flow of charge or charges like electrons.
• What do electrons carry from a source of energy to a component?

  Electrons carry energy from a source of energy to a component.
• How does the battery store energy?

  A battery has a store of chemical potential energy.
• What happens to the energy of electrons when they move through a complete circuit?

  The energy is transferred to the electrons, which move through the wires.
• What is the term used for the movement of charge in a circuit?

  This movement of charge is called a current.
• In which direction does current flow in a circuit?

  Current flows from the positive terminal of the battery to the negative terminal.
• What happens to the energy of electrons as they pass through a bulb?

  Their energy is converted into light.
• What happens to electrons after they transfer energy to the bulb?

  The electrons are pushed back to the battery by the ones behind them.
• What is the significance of the constant flow of electrons in a circuit?

  This constant flow of electrons transferring energy keeps the light bulb on.
• What is potential difference (PD) also known as?

  Potential difference is also known as voltage.
• What does a voltage of 1 volt indicate about energy transfer?

  It means that one joule of energy is given to every coulomb of electrons that pass through it.
• How is potential difference measured?

  Potential difference is measured with a voltmeter.
• How should a voltmeter be connected to measure voltage?

  A voltmeter should be connected in parallel to the components you want to measure the voltage of.
• What does a voltmeter measure when placed across a battery?

  A voltmeter should measure the voltage supplied by the battery, which is 6 volts in this case.
• What does a voltmeter measure when placed across a bulb in a circuit?

  A voltmeter should still measure 6 volts because the electrons lose all that energy as they pass through the bulb.
• What is the equation for potential difference (PD)?

  PD in volts is equal to energy in joules divided by charge in coulombs, or $V =$$\frac{E}{Q}$.
• What does current tell us in a circuit?

  Current tells us the rate of flow of charge.
• What is the equation for current?

  Current in amps equals charge in coulombs divided by time in seconds, or $I =$$\frac{Q}{t}$.
• How is current measured?

  Current is measured with an ammeter.
• How must an ammeter be connected in a circuit?

  An ammeter must be connected in series with the component we want to measure the current for.
• What is resistance in a circuit?

  Resistance is the opposition to the flow of charge or current through components.
• What happens to energy in a bulb with resistance?

  Energy is transferred and light is emitted.
• What happens when the potential difference (PD) is increased in a circuit with a resistor?

  An increasing PD results in a greater current flowing.
• What is the relationship between potential difference (PD) and current?

  PD and current are directly proportional.
• What does a straight line graph of PD versus current indicate about a resistor?

  A straight line graph indicates that a resistor has constant resistance.
• What does the gradient of the PD versus current graph represent?

  The gradient represents the resistance of the resistor.
• What happens to the resistance of a metal filament in a bulb as the PD and current increase?

  The resistance of the metal filament increases with higher PD and higher current.
• Why does resistance change for a metal?

  Resistance changes because metals consist of a lattice of ions surrounded by a sea of delocalized electrons that collide with ions as they flow.
• What happens to the temperature of a metal when current flows through it?

  The metal heats up due to increased collisions between electrons and ions.
• What is a diode?

  A diode only lets current flow through in one direction.
• What does the graph of a diode look like?

  The graph shows high resistance in one direction and low resistance in the other direction.
• What is an LED?


  An LED is a light-emitting diode.
• How does a superconductor behave in terms of resistance?

  A superconductor has a resistance of zero.
• What is the critical temperature in relation to superconductors?

  The critical temperature is the temperature below which a superconductor's resistance falls to zero.
• What is resistivity?


  Resistivity is the resistance of a cube of unit length sides of that material.
• What is the unit of resistivity?

  The unit of resistivity is ohm meters.
• How do you calculate the area of a wire?

  The area is calculated using $A =$$\frac{\pi d^2}{4}$.
• What is the relationship between resistance and length of a wire?

  Resistance is proportional to the length of the wire.
• What is the equation for resistivity?

  The equation for resistivity is $\rho =$$\frac{R A}{L}$.
• What happens to total PD in a series circuit?

  Total PD is shared between components in series.