what colour do you observe when white light passes through a blue and yellow filter?

When white light passes through a blue filter and then a yellow filter, the resulting color you observe is green. This outcome can be understood by examining how filters work and how colors interact with each other.

The Basics of Color Filters

Color filters operate based on the principle of subtractive color mixing. Each filter allows certain wavelengths of light to pass through while absorbing others. In this case, let’s break down what happens with each filter:

Understanding the Blue Filter

A blue filter allows blue wavelengths of light to pass through while absorbing other colors, particularly red and green. So, when white light, which contains all colors, hits the blue filter, only the blue light emerges on the other side.

The Role of the Yellow Filter

Next, when this blue light encounters the yellow filter, things get interesting. A yellow filter allows red and green wavelengths to pass through but absorbs blue. Since the blue light is already present from the first filter, the yellow filter will absorb that blue light, preventing it from passing through.

The Resulting Color

Now, since the blue light is absorbed by the yellow filter, the only colors that can pass through are those that the yellow filter allows—red and green. However, since there is no red light coming from the blue filter, the only color that remains is green. Thus, the combination of the blue filter followed by the yellow filter results in the observation of green light.

Visualizing the Process

• White light (contains all colors) → Blue filter → Blue light passes through.
• Blue light → Yellow filter → Blue light is absorbed, allowing red and green to pass.
• Resulting color observed: Green.

This example illustrates how color mixing works with filters and highlights the fascinating interplay between different wavelengths of light. Understanding these principles can deepen your appreciation for how colors interact in various contexts, from art to science.