(electricity)

• a battery is made up of multiple cells. It supplies energy to the circuit
• a lamp is a radiator in the circuit, applies energy to surroundings
• the wire allows negatively charged electrons to flow through it in the circuit
• current (I) is the rate of flow of charge, it is measured with ammeter (Amps)
• potential difference is the push that makes charge move, energy is supplied to charges
• potential difference is measured with a voltmeter
• resistance (Ohms) resists the flow of charge and reduces the current flowing through it
• the formula for resistance is R = V/I
• in a series circuit, current is constant throughout the circuit. If a component breaks, the rest of the circuit will malfunction
• potential difference in series circuit is shared across all components. Current is also the same for any part of the circuit.
• total resistance is the sum of all the resistors in a circuit
• in a series circuit, adding more components increases the resistance and decreases current (lamps turn dimmer)
• V=E/Q, potential difference = junction/charge
• in a parallel circuit, current is split up at the first junction and rejoined at the second junction
• in a parallel circuit, if a component breaks, the rest of the circuit will continue flowing
• in parallel circuit, potential difference and current is the same in all parts of the circuit
• more components in a parallel circuit means a lower total resistance
• energy transffered = Voltage x current x time(seconds)
• current (I) = charge (Q) / time (t)
• thermal equilibrium is when the rate of heat loss is eaual to heat gain, which causes temperature to stay constant
• advantages + disadvantages of series circuit

  • fewer wires
  • easy control
  • one fails, rest fails
  • no independent control
• advantages + disadvantages of parallel circuit

  • independent control
  • more wires
  • harder control
  • one breaks, rest continues
• potential difference is measured with a voltmeter
• current is measured with an ammeter
• current is directly proportional to voltage, double the current, double the voltage
• for an object to be ohmic, current has to be directly proportional to potential difference
• total resistance = 1/R1 + 1/R2
• a filament lamp is non-ohmic as there is a positive correlation but not direct proportional relationship between current and potential difference
• higher temperatures equals higher resistance in filament lamp. As PD accelerates electrons, their average KE increases and will collide with metal particles more causing them to vibrate faster. This will make it harder for electrons to pass, causing resistance to increase
• a V/I graph for a fixed value resistor is a straight line that goes through the origin (ohmic)
• a V/I graph for a filament lamp is a curved line that goes through the origin (non-ohmic)
• a semi-conducting diode allows current to flow only one direction (forward bias), it can be used to charge batteries
• thermistors are temerature-dependent resistors that will conduct better at higher temperatures, they can be used for electronic thermometers
• LDRs are light-dependent resistors that conduct better at brighter conditiions, and can be used for light meters in cameras