Physics 9 Lesson 55: Color of objects under white light and under colored light
1. Theoretical Summary
1.1. White object, red object, blue object and black object under white light
- Under white light, any colored object will have that color light transmitted to our eyes, (except for black objects). We call the color of the object.
- White objects are capable of scattering all colored light.
1.2. The ability of objects to scatter colored light
– Objects of any color strongly scatter light of that color, but scatter less light of other colors.
– White objects scatter all colored light well.
Black objects are not capable of scattering any colored light.
– When we project three green, white, and red objects with white light on a white background, we see that the three objects are still green, white, and red.
– When shining 3 objects green, white, red with red light, we see:
- The green object is almost the same as the black object ⇒ the green color scatters red light poorly.
- Objects that are white are like red objects ⇒ green scatters red light well.
- The red object is still red ⇒ the red color scatters red light well.
2. Illustrated exercise
Question 1: Place a piece of red glass (or a piece of red cellophane) on a piece of white paper and shine white light on the glass. Looking at the paper through the glass, what color will it be? Why?
- Put a red glass on a white paper and shine white light on the glass, we will see the paper is red.
- Explanation: Red light in a white beam passes through a red glass and then hits a white sheet of paper. The white paper scatters red light well, this red light passes through the red glass in the opposite direction into our eyes, so we see the red paper. (Note that do not look at the glass in the direction of light reflection).
- If we replace the white paper with the blue paper, we will see the black paper. Because the blue paper scatters red light poorly.
Verse 2: Why is it that when we put a red object under white light we see it as red, when we put a blue object under white light we see it as blue?
In a white light beam there are all colors of light. When a red object is placed under white light, it appears red because it scatters red light well in a white beam. Similarly, placing a blue object under white light shows that it appears blue.
3.1. Essay exercises
Question 1: Under the white light, on a picture of a car, we see black tires, the driver is wearing a white shirt, gray hat, and the top of the car has a red flag. Under red light, what color will the objects be?
Verse 2: Under red light and green light, we see a black text. So under the white light, what color is the text?
Question 3: The folk song has a sentence:
Hey, you slap the water on the side
She scooped gold stars moonlight poured away
Why is there a yellow moon in the water?
Question 4: Under the red light we see a person wearing a red shirt. Under the white light, that red shirt is definitely not what color shirt?
3.2. Multiple choice exercises
Question 1: Select the correct answers
A. The red cover sheet is red in any light.
B. A white sheet of paper is still white under red light.
C. Black hair is everywhere.
D. The blue pen box in a dark room still looks blue
Verse 2: When you see a black object,
A. the light that reaches our eyes is white light.
B. the light that reaches our eyes is blue light.
C. the light that reaches our eyes is red light.
D. no light from the object reaches the eye.
Question 3: Choose the correct statement
A. When we see an object of any color (except a black object), that color light enters our eyes.
B. Which color filter is good at absorbing that color light.
C. Shining white light through a yellow filter produces white light.
D. The LEDs emit white light.
Question 4: When we see a white object, the light entering our eyes has the following color:
Through this lesson, the children will be familiar with the knowledge related to the Color of objects under white light and under colored light along with related exercises in many levels from easy to difficult… need to be aware of:
White object, red object, blue object and black object under white light
The ability of objects to scatter colored light