Topic 10 + 11 - ELECTRICITY AND STATIC ELECTRICITY

• What is current?

  Current is the flow of electrons around the circuit. Current only flows when there is a potential difference in the circuit (voltage) and the circuit is complete.
• What is the formula of charge?


  charge = current * time

  
• What is current also known as?

  The rate of charge
• Memorise this.

  
• What is potential difference?

  Potential difference (volts) is the driving force that pushes the charge around the circuit.
• what is the other definition of potential difference?

  The energy transferred per unit charged.
• What is the formula for energy transferred?


  energy transferred = Charge moved * potential difference. (E = Q*V)
• What is the unit for resistance?


  Ohms (Ω).
• What is the formula for potential difference (voltage)?

  potential difference = current * resistance.

  
• What happens to the temperature when the resistance in a circuit increases?

  The temperature increases as the electrons in the wires collide with the ions which causes them to vibrate - releasing energy.
• Where must the ammeter be placed in a circuit?

  In series with the circuit.
• where must the voltmeter be placed in a circuit?

  parallel with the component you are measuring the potential difference of.

  
• What are the steps for the constructing circuits practical?

  1. Setting up the Circuit:Create a loop for the circuit. Arrange the component and ammeter in any order. Place the voltmeter around the component.
  2. Changing Power:Adjust power by changing the potential difference in the circuit.
  3. Collecting Data:Measure how much electricity flows (current) for different power levels. Use both the ammeter and voltmeter.
  4. Graph Time:Plot current and power on a graph. Use a formula to find resistance. See if the component behaves differently with changing power.
• What is LURD? and what component does it correlate with?

  Light intensity up, resistance down. LDRs.
• What is TURD? and what component does it correlate with?

  Temperature up, resistance down. Thermistors.
• What is the function of a diode?

  allows current to flow in one direction.
• What is the correlation found between resistors and potential difference in I-V graphs?(when increasing current).


  Current is directly proportional to the potential difference.

  
• What is the correlation found between Filament lamps and potential difference in I-V graphs? (when increasing current).

  Increasing the current increases the temperature of the lamp - causing the resistance to increase. (It curves at the start and the end).

  
• What is the correlation found between Diodes and potential difference in I-V graphs? (when increasing current).


  Current will only flow in one direction as there is very high resistance in the undesired direction.

  
• What is a series circuit?

  A circuit where the components are connected in a single path, allowing the flow of current through each component one after another.
• what happens to a series circuit when a component is disconnected?


  The circuit breaks and stops working as there is only one path for the current to go through.
• There's a bigger supply p.d. (voltage) when more cells are in series. E.g: 2 x 1.5V = 3V.
• What happens to the current in a series circuit?

  It stays the same. I1 = I2 = I3.
• what happens to the voltage (P.D) in a series circuit?


  It is distributed evenly.
• what happens to a series circuit the more you add resistors and why?


  The total resistance increases because the resistors have to share the Voltage given to them.
• What is a parallel circuit?

  A circuit with multiple paths for current to flow.
• What happens if a component is disconnected in a parallel circuit?

  The other components will continue to function normally as there are different pathways to power them.
• What happens to the voltage (P.D) in a parallel circuit?

  It stays the same across all components. V1 = V2 = V3.
• What happens to the current in a parallel circuit?

  The current is shared amongst each pathway with the current usually distributed unevenly. Total current = I1 + I2.
• In a parallel circuit, the current either splits or rejoins.
• What happens to the resistance in a parallel circuit?

  The resistance decreases as you add more components parallel. As well as resistors. This is because of the current can go in more than one direction
• energy transferred depends on current, voltage and time.
• What is the formula for energy transferred?

  E = I * V * t
• what is the purpose of a fuse?

  to prevent components from overheating due to high amounts of energy being transferred.
• What is power in electricity?

  Power is the energy that is transferred per second from an appliance.
• What is the formula for power (watts)?

  Power = Energy transferred / Time. $I*$$V*$$T/t$
• What is the formula for electrical power?

  Power = Voltage x Current. P = I*V or P = I^2 * R
• What alternating current?

  A type of current in which the charges are constantly changing direction. This means that the positive and negative ends of the voltage keeps on changing direction.
• what is the main UK supply of electricity?

  alternating current - 230V at 50Hz.
• What is direct current?

  The movement of charges in one direction.