Nepedia
Back to Discover
Fluent Reader
⚛️

Neper

physical science Maturity 11-13 Next article →

A neper is a special unit used in science. It helps us measure ratios of physical things. A ratio compares two different amounts of the same thing. For example, it can show how a signal changes. This could be an electronic signal or sound pressure. Scientists use it to track gain or loss.

John Napier
John Napier

This unit is quite important for measuring power. It is a way to see how things grow or shrink.

Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650
Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650

The neper works using a natural logarithm. This is a math tool based on Euler's number. It is different from the decibel. The decibel uses a base-10 logarithm instead. To find the level of two signal amplitudes, you use the natural logarithm of their ratio. For power quantities, you use the natural logarithm of the ratio of two powers.

John Napier
John Napier

This math helps show relative differences. In these units, differences add together. They do not multiply like normal numbers. This makes the math easier for some tasks.

This unit is named after a man named John Napier. He was the inventor of logarithms. His name is on the unit to honor his work.

Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650
Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650

The unit is defined in the international standard ISO 80000. This means it is a recognized way to measure things. It is not part of the International System of Units, or SI. However, the SI system accepts it for use. The International Telecommunication Union also recognizes it.

There are many specific facts about how the neper relates to other units. One neper is equal to the natural logarithm of the number e. The neper is a dimensionless unit. This means it does not have a physical size like a meter. It is also related to the decibel. One neper is equal to about 8.69 decibels.

Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650
Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650

You can also use smaller parts of the unit. A decineper is 0.1 neper. A centineper is 0.01 neper.

You might already know about the decibel. People use decibels to talk about sound levels. The neper is very similar to the decibel. It is used for field quantities like voltage or current. It is also used for pressure in acoustics.

John Napier
John Napier

The centineper can even relate to a log percentage. These units help engineers understand how signals move through systems. They make complex math feel more natural. This helps us study the world of waves and power.

390 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (2)
File:John Napier.jpg
John Napier.jpg
File:Napier, John – Mirifici logarithmorum canonis constructio, 1825 – BEIC 6555650.jpg
Napier, John – Mirifici logarithmorum...
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.