On the informational level, the student becomes acquainted with the law of reflection as it pertains to plane mirrors. First, the student experiences how a plane mirror creates an image that is flipped from left to right. Second, the law of reflection is used to explain the position of an image seen in a mirror in using a toy. The reflection of the toy appears to be behind the mirror! This is due to the fact that our brain tells us that light travels in straight lines coming from the toy, but when we see the toy reflected in the mirror, this is not actually the case. We are fooled when we perceive the cat as being behind the mirror. What we see is called a virtual image.
How does a person's mirror image differ from their actual image? How are virtual images constructed?
- Plane mirror
- Source of light
- Gather the materials which you require for this project. These include a plane mirror (the larger, the better), a toy, and a source of light.
- Copy the chart that you will use to record all of your observations.
- Do not look in the mirror! Start by recording on your chart how you expect a mirror image of your face will be different from an image of your actual face. Do you think it will be identical? If not, how will it differ?
- Now, look at your face in the mirror. Pretend that you are looking at a stranger who happens to be looking back at you. On your chart, record what you observe.
- Touch your left ear with your left hand.Look into the mirror. On which side of the mirror is your left hand? Record your observation.
- Touch your right ear with your right hand. Observe and record. On which side of the mirror is your right hand?
- Put your fingertip on the right-hand side of the mirror.On which side of the mirror is the reflection of your finger? Observe and record.
- Based on your observations, what conclusion do you reach? What kind of a reversal are you experiencing? Record your response.
- Place your toy in front of the mirror. Look carefully into the mirror. Where does it appear to be? In the front? In the back?
- Study the image of the toy; does the image appear to be the same distance behind the mirror as the actual distance the toy sits in front of the mirror? Is this a real or a virtual image?
- What do you conclude from this investigation? Is your brain playing games? How does the law of reflection enter this picture?
- Write up your report. What do you conclude about how our brain and the law of reflection influence our perception of the toy being behind the mirror when we “know” it is in front of the mirror? How do we explain virtual images?