The image above represents energy transfer by radiation.

To compute for energy transfer by radiation, three essential parameters are needed and these parameters are **Emissivity (ε**_{1}), Absorbivity (α_{1}) and** Emissive Power of Black Body (e**_{b}).

The formula for calculating energy transfer by radiation:

q_{net} = e_{b}(ε_{1} – α_{1})

Where:

q_{net} = Energy Transfer by Radiation

ε_{1} = Emissivity

α_{1} = Absorbivity

e_{b} = Emissive Power of Black Body

Let’s solve an example;

Find the energy transfer by radiation when the emissivity is 30, the absorbivity is 10 and the emissive power of black body is 4.

This implies that;

ε_{1} = Emissivity = 30

α_{1} = Absorbivity = 10

e_{b} = Emissive Power of Black Body = 4

q_{net} = e_{b}(ε_{1} – α_{1})

q_{net} = 4(30 – 10)

q_{net} = 4(20)

q_{net} = 80

Therefore, the **energy transfer by radiation **is **80 J.**

**Calculating the Emissivity when the Energy Transfer by Radiation, the Aborbivity and the Emissive Power of Black Body is Given.**

ε_{1} = (^{qnet} / _{eb}) + α_{1}

Where:

ε_{1} = Emissivity

q_{net} = Energy Transfer by Radiation

α_{1} = Absorbivity

e_{b} = Emissive Power of Black Body

Let’s solve an example;

Find the emissivity when the energy transfer by radiation is 28, the absorbivity is 3 and the emissive power of black body is 7.

This implies that;

q_{net} = Energy Transfer by Radiation = 28

α_{1} = Absorbivity = 3

e_{b} = Emissive Power of Black Body = 7

ε_{1} = (^{qnet} / _{eb}) + α_{1}

ε_{1} = (^{28} / _{7}) + 3

ε_{1} = 4 + 3

ε_{1} = 7

Therefore, the **emissivity **is **7**

**Calculating the Aborbivity when the Energy Transfer by Radiation, the Emissivity and Emissive Power of Black Body is Given.**

α_{1} = ε_{1} – (^{qnet} / _{eb})

Where:

α_{1} = Absorbivity

q_{net} = Energy Transfer by Radiation

ε_{1} = Emissivity

e_{b} = Emissive Power of Black Body

Let’s solve an example;

Find the absorbivity when the energy transfer by radiation is 8, the emissivity is 18 and the emissive power of black body is 4.

This implies that;

q_{net} = Energy Transfer by Radiation = 8

ε_{1} = Emissivity = 18

e_{b} = Emissive Power of Black Body = 4

α_{1} = ε_{1} – (^{qnet} / _{eb})

α_{1} = 18 – (^{8} / _{4})

α_{1} = 18 – 2

α_{1} = 16

Therefore, the **absorbivity **is **16.**

**Calculating the Emissive Power of Black Body when the Energy Transfer by Radiation, the Emissivity and Absorbivity is Given.**

e_{b} = ^{qnet} / _{ε1 – α1}

Where:

e_{b} = Emissive Power of Black Body

q_{net} = Energy Transfer by Radiation

ε_{1} = Emissivity

α_{1} = Absorbivity

Let’s solve an example;

Find the emissive power of black body when the energy transfer by radiation is 50, the emissivity is 15 and the absorbivity is 10.

This implies that;

q_{net} = Energy Transfer by Radiation = 50

ε_{1} = Emissivity = 15

α_{1} = Absorbivity = 10

e_{b} = ^{qnet} / _{ε1 – α1}

e_{b} = ^{50} / _{15 – 10}

e_{b} = ^{50} / _{5}

e_{b} = 10

Therefore, the **emissive power of black body **is **10.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the energy transfer by radiation.

Now, Click on **Radiation Heat Transfer **under **Materials and Metallurgical**

Now, Click on **Energy Transfer by Radiation **under **Radiation Heat Transfer**

The screenshot below displays the page or activity to enter your values, to get the answer for the energy transfer by radiation according to the respective parameter which is the **Emissivity (ε**_{1}), Absorbivity (α_{1}) and** Emissive Power of Black Body (e**_{b}).

Now, enter the values appropriately and accordingly for the parameters as required by the **Emissivity (ε**_{1}) is **30**,** Absorbivity (α**_{1}) is **10** and** Emissive Power of Black Body (e**_{b}) is **4**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the energy transfer by radiation and presents the formula, workings and steps too.