Transformers (&Transformer Calculations) (T)

• What is the purpose of step-up transformers?

  They increase the potential difference of an electricity supply.
• What is the purpose of step-down transformers?

  They decrease the potential difference of an electricity supply.
• How can you calculate the potential difference in the secondary coil of a transformer?

  • Use the equation:

  $\frac{V_p}{V_s} =$$\frac{N_p}{N_s}$

  • Where:
  • $V_p$ = potential difference in the primary coil
  • $V_s$ = potential difference in the secondary coil
  • $N_p$ = number of turns in the primary coil
  • $N_s$ = number of turns in the secondary coil
• If a transformer has 200 turns in the primary coil and 50 turns in the secondary coil with a secondary potential difference of 48 volts, what is the primary potential difference?

  192 volts
• How do you calculate the number of turns in the primary coil if a transformer steps up a potential difference from 50 volts to 250 volts with 100 turns in the secondary coil?

  20 turns
• What is the relationship between power in the primary and secondary coils of a transformer?

  • Power is conserved:
  • $P_p =$$P_s$
  • Where:
  • $P_p$ = power in the primary coil
  • $P_s$ = power in the secondary coil
• How is power calculated in a transformer?

  Power = Potential Difference × Current
• If a transformer has a potential difference of 200 volts and a current of 21 amperes in the secondary coil, what is the current in the primary coil if the potential difference is 50 volts?

  0.4 amperes
• How does the National Grid utilize transformers for power transmission?

  • High-voltage cables transmit electrical power from power stations to homes.
  • Step-up transformers increase potential difference to reduce power loss.
  • Step-down transformers decrease potential difference for safe home use.
• What is the purpose of transformers in electricity supply?

  To change the potential difference of an electricity supply.
• Why is it more efficient to use high voltage rather than high current in power transmission?

  High voltage reduces power loss in transmission cables.
• What are the two types of transformers described?

  • Step-up transformer
  • Step-down transformer
• Why do some students find transformers to be a tricky topic?

  Because they think it is a tricky topic.
• What are the two coils in a transformer called?

  • Primary coil
  • Secondary coil
• What is the typical potential difference of the main supply in UK homes?

  230 volts
• What is the role of the iron core in a transformer?

  To increase the strength of the magnetic field.
• Why do transformers only work with alternating current?

  Because they need a changing magnetic field.
• What happens when the primary and secondary coils have the same number of turns?

  Then the potential difference in the secondary coil will be the same as in the primary coil.
• What does it mean if a transformer is 100% efficient?

  It means no energy is wasted.
• What is a step-up transformer?

  • Has more turns in the secondary coil than in the primary coil
  • Induces a greater potential difference in the secondary coil
• If a step-up transformer has twice the number of turns in the secondary coil compared to the primary coil, what is the relationship between their potential differences?

  The potential difference in the secondary coil will be twice that of the primary coil.
• What is a step-down transformer?

  • Has fewer turns in the secondary coil compared to the primary coil
  • Induces a lower potential difference in the secondary coil
• If a step-down transformer has half the number of turns in the secondary coil compared to the primary coil, what is the relationship between their potential differences?

  The potential difference in the secondary coil will be half that of the primary coil.
• What will be covered in the next video regarding transformers?

  • Calculations involving transformers
  • How transformers are used in electrical transmission