Mammoth Memory

Step up or step down transformer

What is a step up transformer or step down transformer? It is easy to remember by visualising the following diagrams:

Step up transformer mnemonic.

Step down transformer mnemonic.

These pictures translate step up as:

Picture of a step up transformer.

A step up transformer has more turns on the secondary coil than the primary coil.


To work out what impact this has on voltage or current, rather than remember what the impact is Mammoth Memory suggests that you try some basic numbers into the formulas you have learnt. It is easier than remembering the results.

The impact of a step up transformer on voltage can be very quickly worked out by using:

`V_1/V_2=N_1/N_2`

Plug some imaginary numbers in.

`(15\ \v\o\l\t\s)/V_2=(10\ \turns)/(100\ \turns)`

`V_2=(15xx100)/10`

`V_2=150\ \v\o\l\t\s`

STEP UP IS AN INCREASE IN VOLTAGE

The impact of this on current can be very quickly worked out by using:

`V_1\ \I_1=V_2\ \I_2`

Using

`V_1=15\ \v\o\l\t\s`  and `V_2=150\ \v\o\l\t\s`

and an imaginary current of 5 amps for `I_1`

We get:

`15xx5=150xxI_2`

`I_2=(15xx5)/150`

`I_2=0.5\ \amps`

STEP UP IS A DECREASE IN CURRENT

These pictures translate step down as:

Picture of a step down transformer.

A step down transformer has less turns on the secondary coil than the primary coil.

The impact of this on voltage can be very quickly worked out by using:

`V_1/V_2=N_1/N_2`

Plug some imaginary numbers in.

`(150\ \v\o\l\t\s)/V_2=(100\ \turns)/(10\ \turns)`

`V_2=(150xx10)/100`

`V_2=15\ \v\o\l\t\s`

STEP DOWN IS A DECREASE IN VOLTAGE

The impact of this on current can be very quickly worked out by using:

`V_1\ \I_1=V_2\ \I_2`

Using

`V_1=150\ \v\o\l\t\s`  and `V_2=15\ \v\o\l\t\s`

and an imaginary current of 5 amps for `I_1`

`5xx150=15xxI_2`

`I_2=(5xx150)/15`

`I_2=50\ \amps`

STEP DOWN IS AN INCREASE IN CURRENT

 

Conclusion

A step up transformer increases voltage.

That is, the voltage at the secondary coil is more than the voltage of the primary coil. Although the voltage increases the current is reduced.

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