Electricity

• Explain an advantage of transmitting electricity at a very high potential difference.


  High pd means low current, which means less thermal energy is transferred to surroundings. This increases the efficiency.
• good conductors of electricity

  • copper.
  • steel.
  • gold.
  • silver.
  • platinum.
  • aluminum.
  • brass.
• bad conductors of electricity

  Materials like glass, plastic, rubber, air, and wood are used as insulators. We are shielded by insulators from the potentially harmful effects of electricity passing through conductors. Electrical circuits can occasionally have dangerously high voltage levels.
• types of circuit structures

  
• gcse electric circut symbols

  
• advantages of a series circut

  In a series circuit, if a lamp breaks or a component is disconnected, the circuit is broken and all the components stop working. Series circuits are useful if you want a warning that one of the components in the circuit has failed. They also use less wiring than parallel circuits.

  
• advantages of parallel circuits

  advantages of a parallel circuits is that a failure of one component does not lead to the failure of the other components. This is because a parallel circuit consists of more than one loop and has to fail in more than one place before the other components fail. The second advantage of parallel circuits is that more components may be added in parallel without the need for more voltage.

  
• disadvantages of series circuits

  One disadvantage of series circuits is that they have a high total resistance, which reduces the current and the power output of the circuit. Another disadvantage is that they are dependent on each component or device working properly. If one of them fails or is disconnected, the whole circuit stops working.
• disadvantages of parallel circuits


  They require more wiring, which can make them more complex and expensive to build. Also each component draws its own current, which adds up and can strain the power source. This means they can use more energy and be less efficient. Also, if one part of the circuit gets damaged or there’s a short circuit, it can be harder to find and fix the problem. Plus, with more branches, the overall resistance decreases, which can lead to overheating if not carefully managed.
• what is the frequency of mains electricity supply in the uk?


  50 hz
• what is potential difference?


  a fancy word for voltage
• what must the circuit be to have a current?


  a closed circuit (connected)
• what is the point of a fuse?


  A fuse provides a built-in fail-safe to the electrical circuit for a device. The fuse contains a thin wire that will melt if the current gets too high. If there is a fault that causes the casing of the device to become live, a large current will flow through the low-resistance earth wire. This high current will cause the fuse to melt. Once the fuse has melted, the circuit is broken and no more current flows through the device. This means the case of the device is no longer live and there is no more risk of electrocution.
• what is a zero error?


  a type of systematic error that occurs when a measuring instrument gives a reading other than zero when it should be zero.
• What type of current is mains electricity in the UK?

  Alternating current (AC)
• What is the frequency of alternating current in the UK?

  50 Hertz
• What is the potential difference of mains electricity in the UK?

  Around 230 volts
• What are the three wires in a three core cable used for mains electricity?

  • Live wire (brown)
  • Neutral wire (blue)
  • Earth wire (green and yellow striped)
• What is the function of the live wire?

  It carries a potential difference of around 230 volts from the supply
• What is the potential difference of the neutral wire?

  Around zero volts compared to the live wire
• What is the purpose of the earth wire?

  It serves as a safety wire to prevent electric shocks
• Why is the live wire considered dangerous?

  It can be fatal if touched due to its potential difference of 230 volts
• What happens if someone touches the live wire?

  A current would flow through the person into the earth, causing electrocution
• Why can appliances with a metal case be dangerous?

  If the live wire comes loose, the case can become live with 230 volts
• How does the earth wire protect against electric shocks?

  It directs excess current to the ground, preventing the case from becoming live
• What happens when the metal case of an appliance becomes live?

  A huge current flows to the earth, causing the fuse to melt and shut off the current
• What are the key functions of the live, neutral, and earth wires?

  • Live wire: Carries 230 volts from the supply
  • Neutral wire: Completes the circuit with zero volts
  • Earth wire: Provides safety by directing excess current to the ground
• What is the potential difference of the earth wire?

  Zero volts
• What is the significance of the potential difference in the live wire compared to the earth wire?

  The live wire has a potential difference of 230 volts, while the earth wire has zero volts
• How does the function of the earth wire prevent electric shocks in appliances?

  It provides a path for excess current to flow safely into the ground
• It is unlikely that all of the electricity that the UK needs can be generated by solar power systems. Explain why


  he UK does not receive as much sunlight as other countries, so solar panels are less efficient in generating energy.  it only generates electricity when the sun is shining, and there is no power at night or on cloudy days.
• what is the relationship with current and p.d for a fixed resistor?

  For a fixed resistor, the potential difference is directly proportional to the current. Doubling the amount of energy into the resistor results in a current twice as fast running through the resistor. This relationship is called Ohm’s Law and is true because the resistance of the resistor is fixed and does not change.

  
• what is the relationship between current and p.d. in a filament bulb?


  In a filament bulb, current increases slower than potential difference because resistance rises as the filament heats up. Higher potential difference raises the filament’s temperature, making it harder for current to flow.

  
• what is the relationship between current and p.d. in a semiconductor diode?


  A semiconductor diode lets current flow in one direction only. In reverse-bias, no current flows due to high resistance. In forward-bias, resistance is high at low voltages but drops at higher voltages, allowing current to flow.

  
• Circuit Types:

  • Series Circuits: One loop, current is the same everywhere.

  • Parallel Circuits: Multiple loops, current splits but voltage is the same in all loops.
• Ohm’s Law.

  Ohm’s Law states that the current (I) through a conductor is directly proportional to the potential difference (V) across it, provided the temperature remains constant.
• What does ‘direct potential difference’ mean?

  means that the flow of electrical energy occurs in one direction only.
• what is the uk frequency and p.d?

  • Frequency: The standard frequency of alternating current (AC) in the UK is 50 Hz (Hertz).

  • Potential Difference (PD): The standard potential difference (voltage) in the UK is 230 V.
• what is the difference between voltage and current?

  Voltage is the electrical potential difference between two points in a circuit, acting as the driving force that pushes electric charge through the circuit. It’s measured in volts (V). Current, on the other hand, is the flow of electric charge (electrons) through a conductor, measured in amperes (A). While voltage provides the energy to move electrons, current measures how much charge flows through the circuit per second.
•  What is voltage?

  Voltage is the electrical potential difference between two points, driving the flow of electric charge.