Why this colour combination?
Using blue, brown and green (and yellow) scientists found that there is no way a colour blind person can confuse which colour is which.
This is how a plug looks to someone who is red-green colour blind.
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-log-table-1.4df6ee6.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-log-table-2.d516bb3.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-anti-log-table-1.b0b0513.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-anti-log-table-2.f89189d.jpg)
Using blue, brown and green (and yellow) scientists found that there is no way a colour blind person can confuse which colour is which.
This is how a plug looks to someone who is red-green colour blind.