Physics Class 10 Practical 22 Important Viva Questions with Answers (To verify laws of refraction using glass slab )
1.What is refraction?
Refraction is the bending of light as it passes from one medium to another with a different density.
2.What are the laws of refraction?
The first law states that the incident ray, the refracted ray, and the normal to the interface of two media all lie in the same plane. The second law, also known as Snell's Law, states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media.
3.What is Snell's Law?
3.What is Snell's Law?
Snell's Law is n1sinθ1=n2sinθ2, where n1 and n2 are the refractive indices of the two media, and θ1 and θ2 are the angles of incidence and refraction, respectively.
4.What apparatus and materials are required for this experiment?
4.What apparatus and materials are required for this experiment?
The experiment requires a glass slab, a drawing board, pins, a protractor, a pencil, and a ruler.
5. Why do we use a glass slab for this experiment?
5. Why do we use a glass slab for this experiment?
A glass slab is used because it has a uniform thickness and its parallel faces make it easier to study the refraction of light.
6. How do you set up the experiment to verify the laws of refraction?
6. How do you set up the experiment to verify the laws of refraction?
Place the glass slab on a sheet of paper, draw the outline of the slab, and mark the normal at the point of incidence. Place pins along the incident ray, trace the refracted ray, and place pins along the emergent ray. Measure the angles of incidence and refraction.
7. What is the angle of incidence?
7. What is the angle of incidence?
The angle of incidence is the angle between the incident ray and the normal at the point of incidence on the surface of the glass slab.
8. What is the angle of refraction?
8. What is the angle of refraction?
The angle of refraction is the angle between the refracted ray and the normal inside the glass slab.
9. What is the refractive index?
9. What is the refractive index?
The refractive index is a measure of how much light bends when it enters a medium from another medium. It is the ratio of the speed of light in vacuum to the speed of light in the medium.
10.How do you measure the angles of incidence and refraction?
10.How do you measure the angles of incidence and refraction?
Use a protractor to measure the angle between the incident ray and the normal for the angle of incidence, and the angle between the refracted ray and the normal for the angle of refraction.
11.What is meant by the term 'normal' in the context of refraction?
11.What is meant by the term 'normal' in the context of refraction?
The normal is an imaginary line perpendicular to the surface at the point of incidence where the light ray strikes the surface.
12. Why is it important to ensure the pins are placed accurately?
12. Why is it important to ensure the pins are placed accurately?
Accurate placement of pins ensures precise tracing of the light paths, leading to accurate measurements of angles, which is crucial for verifying the laws of refraction.
13.How do you verify Snell's Law using the glass slab?
13.How do you verify Snell's Law using the glass slab?
By measuring the angles of incidence and refraction for different angles and calculating the sine ratios, you can verify that the ratio sinθ1/sinθ2 is constant.
14.What observations confirm the first law of refraction?
14.What observations confirm the first law of refraction?
Observations that the incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane confirm the first law of refraction.
15.What could be potential sources of error in this experiment?
15.What could be potential sources of error in this experiment?
Potential sources of error include incorrect placement of pins, inaccurate measurements of angles, and imperfections in the glass slab.
16.How can you minimize errors in this experiment?
16.How can you minimize errors in this experiment?
To minimize errors, ensure accurate placement and alignment of pins, use a precise protractor, and handle the glass slab carefully to avoid scratches and smudges.
17. What is the emergent ray?
17. What is the emergent ray?
The emergent ray is the light ray that exits the glass slab after refraction and is parallel to the incident ray if the slab faces are parallel.
18. Why does the emergent ray appear parallel to the incident ray in a glass slab?
18. Why does the emergent ray appear parallel to the incident ray in a glass slab?
Because the light refracts twice (once entering and once leaving the slab) and the faces of the slab are parallel, causing the deviations to cancel out, making the emergent ray parallel to the incident ray.
19. What is total internal reflection?
19. What is total internal reflection?
Total internal reflection occurs when the angle of incidence exceeds the critical angle, causing the light to reflect entirely back into the medium rather than refracting out of it.
20. How does the thickness of the glass slab affect the experiment?
20. How does the thickness of the glass slab affect the experiment?
The thickness does not affect the angles of incidence and refraction, but it does affect the lateral displacement of the light ray as it passes through the slab.