Replacing a light bulb may not be as straight forward as it used to be. Nowadays there are many different types of light bulbs to choose from, including incandescent bulbs, halogen bulbs, fluorescent bulbs and so many different types of LED lights.

There are many criteria to consider when selecting a light bulb including:

- The
**amount of light (aka luminous flux)**the bulb provides, expressed in lumens (**lm**) - The
**power consumption over 1000 hours**expressed in**kW/1000h** - The
**energy rating**of the light bulb given as a rating**between A and G**

#### Energy Rating Ratio

The energy rating (aka Energy Efficiency class) of a light bulb is used to give an indication of **how efficient / eco-friendly** a light bulb is.

To workout the energy rating of a light bulb, we first need to calculate its lumens to watt **efficiency ratio** based on the following formula:

We can then use this ratio to determine the energy rating of the bulb using the following table:

Energy Rating |
Efficiency Ratio |

210 or above | |

185 or above | |

160 or above | |

135 or above | |

110 or above | |

85 or above | |

Below 85 |

#### Python Challenge

Your task consists of writing a Python program that asks the user to **enter two values**:

- The light output (luminous flux) of a light bulb (in lumens, lm)
- The power consumption of the light bulb over 1000h (in kW/1000h)

Your program should then **calculate the efficiency ratio** of the light bulb to then **output its energy rating** as a label from A to G.

#### Python Code

You should complete your code below:

#### Test Plan

Once your code is complete, make sure it is working as expected by completing the following test plan:

Test # | Input Values | Expected Output | Actual Output | |

#1 | Light Output: 1600lm Power Consumption: 8kW/1000h |
Energy Rating: B | ||

#2 | Light Output: 1800lm Power Consumption: 5kW/1000h |
Energy Rating: A | ||

#3 | Light Output: 840lm Power Consumption: 4kW/1000h |
Energy Rating: A | ||

#4 | Light Output: 1100lm Power Consumption: 12kW/1000h |
Energy Rating: F |

#### Solution...

The solution for this challenge is available to full members!Find out how to become a member:

➤ Members' Area