Question

Use a ruler and a protractor to find the image by refraction in the following cases. Assume an air-glass interface. Use a refractive index of 1 for air and of 1.5 for glass. (Hint: Use Snell’s law at the interface.)

a. Refraction results in total internal reflection.
b. Refraction results in a real and inverted image.
c. Refraction results in a virtual and erect image.
d. Refraction results in no change in the direction of light.

Answer 1

To determine the image by refraction at an air-glass interface, Snell's law is used, observing different phenomena like total internal reflection, the formation of real or virtual images, or no change in the light's direction depending on the angle of incidence. Therefore, the correct answer is option d. Refraction results in no change in the direction of light.

Step-by-step explanation:

When using a ruler and a protractor to find the image by refraction, we must consider the law of refraction, or Snell's law. This law is applied at the interface between two media with different indices of refraction, such as air and glass. In the cases provided:

• a. Refraction results in total internal reflection: This occurs when the angle of incidence in the glass (with higher refractive index) is greater than the critical angle for the air-glass interface. Since the angle of refraction would be 90 degrees, there's no refracted ray entering the air, and all the light is reflected inside the glass.
• b. Refraction results in a real and inverted image: A real image is formed when refracted rays converge and pass through the image point. In the air-glass scenario, this can happen when light rays entering the glass are refracted at angles that cause them to meet after crossing the boundary.
• c. Refraction results in a virtual and erect image: A virtual image appears when refracted rays diverge, but seem to come from a point behind the glass interface. This typically occurs when viewing an object through a thicker glass at a shallow angle.
• d. Refraction results in no change in the direction of light: This will only occur if the incident light is perpendicular to the interface, meaning there's no change in the direction as the light enters the glass from the air.

To apply Snell's law n₁ sin θ₁ = n₂ sin θ₂, where n₁ and n₂ are the refractive indices of air and glass, respectively, and θ₁ and θ₂ are the angles of incidence and refraction.

Therefore, the correct answer is option d. Refraction results in no change in the direction of light.