Light Waves Flashcards
Define ‘normal’ in the context of reflection.
The normal is an imaginary line drawn perpendicular to the reflecting surface at the point where the incident ray strikes.
Define ‘angle of incidence’ in the context of reflection.
The angle of incidence is the angle between the incident ray and the normal at the point of reflection.
Define ‘angle of reflection’ in the context of reflection.
The angle of reflection is the angle between the reflected ray and the normal at the point of reflection.
State the law of reflection.
The law of reflection states that the angle of incidence is equal to the angle of reflection.
How can you use the law of reflection to solve problems in optics?
By measuring or calculating the angle of incidence, you can determine the angle of reflection since they are equal.
Describe an experiment to illustrate the law of reflection.
- Place a plane mirror on a sheet of paper. 2. Draw the normal at the point where the incident ray strikes. 3. Shine a light ray onto the mirror and mark its path. 4. Mark the reflected ray’s path. 5. Measure the angles of incidence and reflection and verify they are equal.
Alternate-style question: How can you ensure accurate angle measurement during the reflection experiment?
Use a protractor to measure the angles carefully, ensure the mirror is stationary and placed perpendicular to the surface, and keep the light ray narrow.
Describe an experiment to find the position of an optical image formed by a plane mirror.
- Place a plane mirror vertically on a sheet of paper. 2. Place an object (like a pin) in front of the mirror. 3. Use two pins to locate the reflected image by sighting along the reflected ray. 4. Extend the reflected rays backward to meet. This point is the virtual image position.
Alternate-style question: How can you verify that the optical image formed by a plane mirror is the same size as the object?
Measure the distance of the object from the mirror and compare it to the distance of the virtual image behind the mirror using a ruler. They should be equal.
State the characteristics of an image formed by a plane mirror.
The image is virtual, upright, of the same size as the object, laterally inverted, and the same distance behind the mirror as the object is in front.
How do you distinguish between a virtual and a real image?
A virtual image cannot be projected onto a screen and is formed by the apparent divergence of light rays, while a real image can be projected and is formed by actual convergence of light rays.
Explain how to calculate the angle of reflection when given the angle of incidence.
Since the angle of reflection equals the angle of incidence, you can directly use the given angle of incidence as the angle of reflection.
Why is the normal line crucial in reflection experiments?
The normal serves as the reference line for measuring angles of incidence and reflection accurately.
Alternate-style question: Why is it important to draw rays accurately in reflection experiments?
Accurate rays ensure correct measurement of angles and verification of the law of reflection, reducing experimental error.
