2.5.2 Transformers

• What is the purpose of transformers in the National Grid?

  Efficient electricity transmission
• The turns ratio in a transformer is the ratio of the number of turns in the secondary coil to the number of turns in the primary coil.


  True
• Match the transformer type with its primary use:

  Step-up Transformer ↔️ Long-distance transmission

  Step-down Transformer ↔️ Safe voltage for homes
• What type of current do transformers operate on?

  Alternating current (AC)
• Transformers change the power of an alternating current.

  False
• Transformers operate based on the principle of electromagnetic induction
• What formula is used to calculate voltage and current changes in transformers using the turns ratio?

  \frac{V_{s}}{V_{p}} = \frac{N_{s}}{N_{p}}</latex>
• Transformers require regular maintenance to ensure safe operation.


  True
• Transformers in the National Grid step up voltage at power stations to reduce energy loss due to resistance
• What is the role of transformers at substations in the National Grid?

  Step down voltage
• What material is the core of a transformer made of?

  Laminated iron
• The secondary coil in a transformer induces a voltage based on the turn ratio with the primary coil.


  True
• When alternating current flows through the primary coil, it generates a changing magnetic field in the iron core
• What effect does a step-down transformer have on voltage?

  Decreases voltage
• Match the transformer type with its turn ratio and voltage effect:

  Step-up Transformer ↔️ $\frac{N_{s}}{N_{p}} > 1$, Increases voltage

  Step-down Transformer ↔️ $\frac{N_{s}}{N_{p}} < 1$, Decreases voltage
• Step-up transformers have a secondary coil with more turns than the primary
• Step-down transformers have a secondary coil with fewer turns than the primary
• Match the transformer type with its effect on voltage:

  Step-up ↔️ Increases

  Step-down ↔️ Decreases
• At power stations, step-up transformers increase voltage to reduce energy loss during transmission.


  True
• Match the transformer component with its function:

  Core ↔️ Enhances magnetic field

  Primary Coil ↔️ Generates magnetic field

  Secondary Coil ↔️ Induces voltage
• A changing magnetic field in the iron core induces a voltage in the secondary coil.


  True
• Match the transformer type with its use case:

  Step-up ↔️ Power Stations

  Step-down ↔️ Substations
• The formula relating voltages and turns ratio is \frac{V_{s}}{V_{p}} = \frac{N_{s}}{N_{p}}</latex>, where $V_{s}$ is the voltage in the secondary
• In an ideal transformer, the relationship between voltage and current is given by $\frac{V_{s}}{V_{p}} =$$\frac{I_{p}}{I_{s}}$, where $I_{p}$ is the primary current
• What does a step-down transformer do to voltage?

  Decreases it
• The turns ratio in an ideal transformer determines how voltage and current are transformed.


  True
• Match the type of transformer with its effect on voltage and current:

  Step-up ↔️ Increases voltage, decreases current

  Step-down ↔️ Decreases voltage, increases current
• A transformer has a primary current of 5A and a turns ratio of 2. What is the secondary current?

  2.5A
• What type of transformers are used at substations to reduce voltage for safe distribution?

  Step-down transformers
• What is the primary purpose of transformers in the National Grid?

  Transmit electricity efficiently
• Match the stage in the National Grid with its voltage use:

  Power Stations ↔️ Step up

  Substations ↔️ Step down
• What is the function of the core in a transformer?

  Concentrate magnetic field
• Substations in the National Grid are used to step down the voltage for safe and practical distribution
• What material is the core of a transformer made of?

  Laminated iron
• The primary coil of a transformer is connected to the AC input
• Transformers operate on Faraday's law of electromagnetic induction.


  True
• Match the transformer type with its effect on voltage:

  Step-up ↔️ Increases

  Step-down ↔️ Decreases
• Step-up transformers have more turns in the secondary coil than in the primary coil.


  True
• What is the turns ratio condition for a step-down transformer?

  $\frac{N_{s}}{N_{p}} < 1$
• Which type of transformer has a turns ratio greater than 1?

  Step-up