Open in App Suggest Corrections 0 Glass slab is a substance or sheet made of a glass material having 3 dimensions that is length breadth and height, it is cuboidal shaped. It does not deviate nor does it disperse the light rays passing through it. This means that the incident and the emergent ray emerging from the glass slab are parallel. The glass slab only and only produces a lateral or (sideways) shift or displacement to the direction of light. As we can observe and see below, the refraction or bending of light rays through a glass slab takes place at the two parallel and equal and opposite surfaces. As we can see and observe the incident ray which falls on one of the parallel surfaces of the slab first undergoes refraction at the PS surface and the refracted ray bends towards the normal, and again it is incident on the other surface which is equal to the first one and that is QR. Through a glass slab, the light before coming back to the air suffers refraction two times. At the second time, the refracted ray bends away from the normal. If the light is incident at right angles then it will pass through the glass slab without any deviation. The emergent ray as we can see has emerged parallel to the before an incident ray of light. This is a characteristic property of a glass slab as it has two opposite and parallel equal faces from which the rays emerge. Now we can easily trace the ray of light after passing through glass slab as follows: Incident Ray- The ray of light falling obliquely on one of the surfaces of the glass slab is known or referred to as the incident ray. We can use many light sources to generate incident rays for observing the refraction occurring through a glass slab. Refracted Ray- The ray of light that emerges after refraction through one of the surfaces on which the incident ray has struck. The refracted ray moves toward normal in case the light enters from rarer medium to denser, or it moves further away from the normal ray in case the light travels from denser to rarer medium. Normal Ray- Two normal rays are drawn at the two opposite parallel surfaces of the slab from where we measure the angles of incidence, refraction, and emergence respectively. Emergent Ray- The ray of light which emerges from another opposite face of the glass slab is called the emergent ray. It has been seen or observed that emergent ray emerges somewhat parallel to the path from where incident ray could have emerged if it would not have experienced any change. Lateral DisplacementThere is a distance between the incident and the emergent ray that emerged. This distance is known as lateral displacement or shift. We consider it a shift from the original path from where the incident ray of light was supposed to emerge if it would not have experienced or undergone any refraction. The thicker the glass slab is the more shift or displacement from the original incident position is observed. It depends upon the thickness of the given glass slab and on the angle of incidence and refraction respectively. The formula of lateral displacement is given below:
Laws of RefractionBased on the refraction through different surfaces, some common properties were observed in all. There are given two laws of refraction as given and stated below which at the sight of refraction the light follows and what we see is the refracted image formed of the object.
Sample ProblemsQuestion 1: What is the constant value if the angle of refraction is given to be 15° and the angle of incidence is 35°? Solution:
Question 2: What is the value of the sin of angle of incidence if the angle of refraction is given to be 35°? The constant is assumed to be 1.57. Solution:
Question 3:What is the constant value if the angle of incidence is 45° and the angle of refraction is given to be 60°? Solution:
Question 4: What will happen to the emergent ray that will come from the surface of glass slab if the angle of incidence is perpendicular or along the normal ray? Answer:
Question 5: Does the light ray that travels from the surface of the glass slab undergo any dispersion or deviation? Answer:
Question 6: By applying the lateral displacement formula find out the lateral displacement through a glass slab which has a thickness of 5cm and the angle of incidence is 45° and refraction is 30°. Solution:
Question 7: By applying the lateral displacement formula find out the lateral displacement through a glass slab which has a thickness of 10 cm and the angle of incidence is 60° and refraction is 45°. Solution:
Question 8: By applying the lateral displacement formula find out the thickness of a given glass slab which has a shift or lateral displacement of 5 cm and the angle of incidence is 45° and refraction is 30°. Solution:
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