# What is coloration efficiency?

## What is coloration efficiency?

The coloration efficiency (CE), defined as the change in optical density per injected charge density at a particular wavelength, can be a strong predictor of electrochemical stability and speed.

## What is four-color& five color problem?

Precise formulation of the theorem If we wanted those regions to receive the same color, then five colors would be required, since the two A regions together are adjacent to four other regions, each of which is adjacent to all the others.

**What is four-color problem in graph theory?**

The four-color theorem states that any map in a plane can be colored using four-colors in such a way that regions sharing a common boundary (other than a single point) do not share the same color. This problem is sometimes also called Guthrie’s problem after F. Guthrie, who first conjectured the theorem in 1852.

### How many colors does a map need?

four colors

As mentioned above, the four-color theorem states that only four colors are needed to ensure adjacent regions have different colors — the point being to make sure that each is distinguishable from the other.

### How is coloration efficiency calculated?

Using 95% of the total transmittance change at λmax as reference point, coloration efficiencies, η = ΔA(λmax)/Q, were calculated as 143 and 150 cm2 C−1 respectively for the PB/PW and PW/PB electrochromic transitions.

**Who proved the five color theorem?**

Percy John Heawood

The Five color theorem is a theorem from Graph theory. It states that any plane which is separated into regions, such as a map, can be colored with no more than five colors. It was first stated by Alfred Kempe in 1890, and proved by Percy John Heawood eleven years later.

## How is the four color theorem used today?

One of the 4 Color Theorem most notable applications is in mobile phone masts. These masts all cover certain areas with some overlap meaning that they can’t all transmit on the same frequency. A simple method of ensuring that no two masts that overlap have the same frequency is to give them all a different frequency.