Fuses and earthing

• What is the biggest city in Africa?

  Lagos
• In which country is Lagos located?

  Nigeria
• What is the population trend in Lagos?

  It is rapidly increasing.
• What is the significance of slums in Lagos?

  They are important for urban growth.
• What do earthing and fuses prevent in electrical systems?

  They prevent electrical overloads.
• What can cause surges in current?

  Changes in a circuit or faults.
• How do surges in current affect circuits?

  They can lead to overheating and fires.
• What happens when a fault develops in an electrical appliance?

  It can cause electrical shocks.
• How does a larger current affect cables?

  It requires thicker cables to prevent overheating.
• What is the purpose of rating fuses in electrical systems?

  To prevent excessive current flow.
• What is the relationship between current and cable thickness?

  Thicker cables are needed for larger currents.
• What is the risk of a large current flowing through a circuit?

  It can cause fires and electrical shocks.
• What do household fuses protect against?

  Electrical overloads and faults.
• What are the key functions of earthing and fuses in electrical systems?

  • Prevent electrical overloads
  • Protect against electrical shocks
  • Ensure safety in electrical appliances
• What are the consequences of a fault in an electrical appliance?

  • Can cause electrical shocks
  • May lead to overheating
  • Risk of fire hazards
• How does the size of the current affect the choice of cables?

  • Larger currents require thicker cables
  • Thicker cables prevent overheating
  • Ensures safety in electrical installations
• What happens during a surge in current?

  • Can lead to overheating
  • May cause circuit damage
  • Risks electrical fires
• What is the importance of rating fuses in electrical systems?

  • Prevents excessive current flow
  • Protects appliances from damage
  • Ensures safety in electrical systems
• What are the implications of using household fuses?

  • Protects against electrical overloads
  • Ensures safety in home wiring
  • Prevents appliance damage
• What do faults show in electrical systems?

  Live wire touching the metal case
• What happens when a large current flows through the earth wire?

  It melts the fuse
• What do household fuses do?

  They blow when overloaded
• How do circuit breakers work compared to fuses?

  They protect wiring without blowing
• What is the advantage of using circuit breakers over fuses?

  They can be reset after tripping
• Why are circuit breakers considered safer than fuses?

  They can be reset instead of replaced
• What is the purpose of insulating materials in electrical applications?

  To reduce the risk of electric shock
• What does "earthing" mean in electrical systems?

  Connecting the case to the earth wire
• What happens if an earthed conductor becomes live?

  It cannot become live
• What is the significance of double insulation in electrical devices?

  It reduces the risk of electric shock
• How does a plastic casing affect the safety of an electrical appliance?

  It provides double insulation
• What is the total resistance of two bulbs in series with resistance 20 ohms each?

  40 ohms
• What is the formula for calculating total resistance in series?

  Total resistance = R1 + R2
• What is the unit of current?

  Ampere
• What does Ohm's Law state?

  Voltage = Current × Resistance
• If a circuit has a voltage of 10V and a resistance of 5 ohms, what is the current?

  2 Amperes
• How does increasing resistance affect current in a circuit?

  It decreases the current
• What is the total resistance of two resistors in parallel, each with resistance 10 ohms?

  5 ohms
• What is the formula for calculating total resistance in parallel?

  1/R_total = 1/R1 + 1/R2
• What is the effect of connecting batteries in series?

  Increases total voltage
• What happens to the total resistance when more resistors are added in parallel?

  Total resistance decreases