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Difference between revisions of "Electrical Transformer"

(Created page with "==Key Stage 4== ===Meaning=== right|300px|thumb|A picture of a '''transformer''' in the [[National Grid.]] A '''transformer''' is a device used to tak...")
 
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===About Transformers===
 
===About Transformers===
 
: '''Transformers''' use a coil of [[wire]] in one [[circuit]] (primary coil) wrapped around a [[Soft Iron|soft iron]] core and second coil of [[wire]] in another [[circuit]] (secondary coil). When an [[Alternating Current|alternating current]] passes through the primary coil this creates a changing [[Magnetic Field|magnetic field]] which induces an alternating [[Potential Difference|potential difference]] across the secondary coil. If that secondary coil is connected in a [[circuit]] it will produce an [[Alternating Current|alternating current]].
 
: '''Transformers''' use a coil of [[wire]] in one [[circuit]] (primary coil) wrapped around a [[Soft Iron|soft iron]] core and second coil of [[wire]] in another [[circuit]] (secondary coil). When an [[Alternating Current|alternating current]] passes through the primary coil this creates a changing [[Magnetic Field|magnetic field]] which induces an alternating [[Potential Difference|potential difference]] across the secondary coil. If that secondary coil is connected in a [[circuit]] it will produce an [[Alternating Current|alternating current]].
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: There are two types of '''transformer''' you should know:
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:*Step Up '''Transformer''' - A '''transformer''' which increase the [[Potential Difference|potential difference]].
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:*Step Down '''Transformer''' - A '''transformer''' which decrease the [[Potential Difference|potential difference]].
 +
: Step up '''transformers''' are used in the [[National Grid]] to increase the [[Potential Difference|potential difference]] and decrease the [[Electrical Current|current]] for long distance transmission.
  
 
{| class="wikitable"
 
{| class="wikitable"
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|-
 
|-
 
| style="height:20px; width:200px; text-align:center;" |This [[diagram]] of a '''transformer''' shows that an [[Alternating Current|alternating current]] in the primary coil induces an alternating [[Potential Difference|potential difference]] in the secondary coil.
 
| style="height:20px; width:200px; text-align:center;" |This [[diagram]] of a '''transformer''' shows that an [[Alternating Current|alternating current]] in the primary coil induces an alternating [[Potential Difference|potential difference]] in the secondary coil.
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|}
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===Equation===
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''NB: You must be able to use this equation, but you do not need to remember it.''
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 +
(Primary Potential Difference)/(Secondary Potential Difference)=(Primary Coils)/(Secondary Coils)
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<math>\frac{V_p}{V_s} = \frac{n_p}{n_s}</math>
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<math>V_p</math> = The [[Potential Difference|potential difference]] across the primary coil.
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<math>V_s</math> = The [[Potential Difference|potential difference]] across the secondary coil.
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<math>n_p</math> = The number of loops on the primary coil.
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<math>n_s</math> = The number of loops on the secondary coil.
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 +
===Example Calculations===
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{| class="wikitable"
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|[[File:TransformerQ1.png|center|300px]]
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|[[File:TransformerQ2.png|center|300px]]
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|-
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| style="height:20px; width: 300px; text-align:center;" |Calculate the [[Potential Difference|potential difference]] across the secondary coil.
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| style="height:20px; width: 300px; text-align:center;" |Calculate the [[Potential Difference|potential difference]] across the secondary coil.
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|-
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| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in [[SI Unit]]s.'''
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<math>V_p</math> = 3V
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<math>n_p</math> = 4 coils
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<math>n_s</math> = 8 coils
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| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in [[SI Unit]]s.'''
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 +
<math>V_p</math> = 9V
 +
 +
<math>n_p</math> = 6 coils
 +
 +
<math>n_s</math> = 8 coils
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|-
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| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
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<math>\frac{V_p}{V_s} = \frac{n_p}{n_s}</math>
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<math>\frac{3}{V_s} = \frac{4}{8}</math>
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<math>\frac{3}{V_s} = 0.5</math>
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 +
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
 +
 +
<math>\frac{V_p}{V_s} = \frac{n_p}{n_s}</math>
 +
 +
<math>\frac{9}{V_s} = \frac{6}{8}</math>
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 +
<math>\frac{9}{V_s} = 0.75</math>
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|-
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| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
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<math>0.5 \times V_s = 3</math>
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<math>V_s = 6V</math>
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| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
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<math>0.75 \times V_s = 9</math>
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<math>V_s = 12V</math>
 
|}
 
|}

Revision as of 14:04, 5 March 2019

Key Stage 4

Meaning

A picture of a transformer in the National Grid.

A transformer is a device used to take the alternating current in a circuit and transmit it to another circuit to produce electricity with a different potential difference and current.

About Transformers

Transformers use a coil of wire in one circuit (primary coil) wrapped around a soft iron core and second coil of wire in another circuit (secondary coil). When an alternating current passes through the primary coil this creates a changing magnetic field which induces an alternating potential difference across the secondary coil. If that secondary coil is connected in a circuit it will produce an alternating current.
There are two types of transformer you should know:
Step up transformers are used in the National Grid to increase the potential difference and decrease the current for long distance transmission.
TransformerDiagram.png
This diagram of a transformer shows that an alternating current in the primary coil induces an alternating potential difference in the secondary coil.

Equation

NB: You must be able to use this equation, but you do not need to remember it.

(Primary Potential Difference)/(Secondary Potential Difference)=(Primary Coils)/(Secondary Coils)

\(\frac{V_p}{V_s} = \frac{n_p}{n_s}\)

\(V_p\) = The potential difference across the primary coil.

\(V_s\) = The potential difference across the secondary coil.

\(n_p\) = The number of loops on the primary coil.

\(n_s\) = The number of loops on the secondary coil.

Example Calculations

TransformerQ1.png
TransformerQ2.png
Calculate the potential difference across the secondary coil. Calculate the potential difference across the secondary coil.
1. State the known quantities in SI Units.

\(V_p\) = 3V

\(n_p\) = 4 coils

\(n_s\) = 8 coils

1. State the known quantities in SI Units.

\(V_p\) = 9V

\(n_p\) = 6 coils

\(n_s\) = 8 coils

2. Substitute the numbers and evaluate.

\(\frac{V_p}{V_s} = \frac{n_p}{n_s}\)

\(\frac{3}{V_s} = \frac{4}{8}\)

\(\frac{3}{V_s} = 0.5\)

2. Substitute the numbers and evaluate.

\(\frac{V_p}{V_s} = \frac{n_p}{n_s}\)

\(\frac{9}{V_s} = \frac{6}{8}\)

\(\frac{9}{V_s} = 0.75\)

3. Rearrange the equation and solve.

\(0.5 \times V_s = 3\)

\(V_s = 6V\)

3. Rearrange the equation and solve.

\(0.75 \times V_s = 9\)

\(V_s = 12V\)

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