When a light ray enters into glass medium from water at an angle of incidence 0º, what would be the angle of refraction?

Question

When a light ray enters into glass medium from water at an angle of incidence 0&ordm;, what would be the angle of refraction?

Prepp Team · Accepted Answer

Understanding Light Refraction at 0&deg; Incidence This question asks about the angle of refraction when a light ray travels from water into glass at a specific angle of incidence: 0&deg;. Let's break down what happens when light passes from one medium to another. What is Refraction? Refraction is the bending of light as it passes from one transparent medium into another. This bending occurs because light travels at different speeds in different materials. The amount of bending depends on the properties of the two media and the angle at which the light hits the boundary between them. The relationship between the angle of incidence (the angle between the incoming ray and the normal to the surface) and the angle of refraction (the angle between the refracted ray and the normal) is described by Snell's Law. Applying Snell's Law to 0&deg; Incidence Snell's Law states: $n_1 \sin \theta_1 = n_2 \sin \theta_2$ Where: $n_1$ is the refractive index of the first medium (water in this case). $\theta_1$ is the angle of incidence (given as 0&deg;). $n_2$ is the refractive index of the second medium (glass in this case). $\theta_2$ is the angle of refraction (what we want to find). In this problem, the angle of incidence $\theta_1$ is given as 0&deg;. Let's plug this into Snell's Law: $n_1 \sin 0^\circ = n_2 \sin \theta_2$ We know that the sine of 0&deg; is 0 ($\sin 0^\circ = 0$). So the equation becomes: $n_1 \times 0 = n_2 \sin \theta_2$ $0 = n_2 \sin \theta_2$ Since $n_2$ (the refractive index of glass) is a non-zero value, for the product $n_2 \sin \theta_2$ to be zero, $\sin \theta_2$ must be zero. $\sin \theta_2 = 0$ The angle whose sine is 0 is 0&deg; (within the practical range of angles for refraction, which is typically 0&deg; to 90&deg;). Therefore, the angle of refraction $\theta_2$ is 0&deg;. $\theta_2 = 0^\circ$ Physical Explanation When a light ray strikes the boundary between two media perpendicularly, it is incident along the normal. In this specific case, the angle of incidence is 0&deg;. When light is incident normally on a surface, it does not bend; it passes straight through into the second medium. This is true regardless of the refractive indices of the two media. The direction of the light ray does not change, meaning the angle of refraction is also 0&deg;. Analyzing the Options Let's look at the given options based on our understanding: Option 1: 90&deg;. This would mean the ray travels along the surface, which is not what happens at 0&deg; incidence. Option 2: 45&deg;. This implies bending, which doesn't occur at normal incidence. Option 3: 0&deg;. This matches our derivation from Snell's Law and the physical principle of normal incidence. Option 4: The ray will not enter at all. This is incorrect; light generally enters a transparent medium unless conditions for total internal reflection are met (which is not the case here). Based on the principles of refraction and Snell's Law, the angle of refraction is 0&deg; when the angle of incidence is 0&deg;. Parameter Value Medium 1 Water Medium 2 Glass Angle of Incidence ($\theta_1$) 0&deg; Angle of Refraction ($\theta_2$) ? Snell's Law $n_1 \sin \theta_1 = n_2 \sin \theta_2$ Substituting $\theta_1 = 0^\circ$: $n_1 \sin 0^\circ = n_2 \sin \theta_2$ $n_1 \times 0 = n_2 \sin \theta_2$ $0 = n_2 \sin \theta_2$ Since $n_2 \neq 0$, we must have $\sin \theta_2 = 0$, which implies $\theta_2 = 0^\circ$. Conclusion on Angle of Refraction When a light ray enters glass from water at an angle of incidence of 0&deg;, it passes straight through without any deviation. Therefore, the angle of refraction is also 0&deg;. Revision Table: Light Refraction Basics Concept Description Refraction Bending of light as it passes from one medium to another. Angle of Incidence Angle between incident ray and the normal at the point of incidence. Angle of Refraction Angle between refracted ray and the normal at the point of refraction. Normal Incidence When the angle of incidence is 0&deg; (ray strikes perpendicular to the surface). Snell's Law Mathematical relation between angles of incidence/refraction and refractive indices: $n_1 \sin \theta_1 = n_2 \sin \theta_2$. Refractive Index (n) A measure of how much a medium slows down light; affects the amount of bending. Additional Information: Refraction and Optical Density The bending of light during refraction is related to the change in optical density between the two media. Optical density is related to the refractive index. A medium with a higher refractive index is optically denser than a medium with a lower refractive index. When light travels from a rarer medium (lower $n$) to a denser medium (higher $n$), it bends towards the normal. The angle of refraction is less than the angle of incidence ($\theta_2 < \theta_1$). When light travels from a denser medium (higher $n$) to a rarer medium (lower $n$), it bends away from the normal. The angle of refraction is greater than the angle of incidence ($\theta_2 > \theta_1$). However, these rules about bending towards or away from the normal apply only when the angle of incidence is not 0&deg;. At 0&deg; incidence, there is no bending, regardless of the change in optical density. The ray simply passes straight through the interface along the normal.

Prepp Team · Answer

90 &compfn;

Prepp Team · Answer

45 &compfn;

Prepp Team · Answer

The ray will not enter at all

Understanding Light Refraction at 0° Incidence

What is Refraction?

Applying Snell's Law to 0° Incidence

Physical Explanation

Analyzing the Options

Conclusion on Angle of Refraction

Revision Table: Light Refraction Basics

Additional Information: Refraction and Optical Density

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Parameter	Value
Medium 1	Water
Medium 2	Glass
Angle of Incidence (\(\theta_1\))	0°
Angle of Refraction (\(\theta_2\))	?
Snell's Law	\(n_1 \sin \theta_1 = n_2 \sin \theta_2\)

Concept	Description
Refraction	Bending of light as it passes from one medium to another.
Angle of Incidence	Angle between incident ray and the normal at the point of incidence.
Angle of Refraction	Angle between refracted ray and the normal at the point of refraction.
Normal Incidence	When the angle of incidence is 0° (ray strikes perpendicular to the surface).
Snell's Law	Mathematical relation between angles of incidence/refraction and refractive indices: \(n_1 \sin \theta_1 = n_2 \sin \theta_2\).
Refractive Index (n)	A measure of how much a medium slows down light; affects the amount of bending.