Light – Reflection and Refraction: Class 10 Science Q&A · Page 3
47 free answers on Light – Reflection and Refraction (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10CBSE
Light enters from air to glass, having a refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 x 108 ms-1.
Answer- Refractive index of a medium (nm) = Speed of light in vacuum/Speed of light in the medium Speed of light in vacuum (c) = 3 × 108 m/s Refractive index of glass (ng) = 1.50 Speed of light in the glass (v) = Speed of light in vacuum/ Refractive index of glass = c/ng =3 × 108/1.50 = 2x 108 ms-1.
- ScienceClass 10CBSE
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?
Answer- The light ray bends towards the normal. When a light ray enters from an optically rarer medium (which has a low refractive index) to an optically denser medium (which has a high refractive index), its speed slows down and bends towards the normal. As water is optically denser than air, a ray of light entering from air into water will bend towards the normal.
- ScienceClass 10CBSE
Find the focal length of a convex mirror whose radius of curvature is 32 cm.
Answer- Radius of curvature (R) = 32 cm Radius of curvature = 2 × Focal length (f) R= 2f f = R/2 = 32/2 = 16 Therefore, the focal length of the given convex mirror is 16 cm.
- ScienceClass 10CBSE
Why do we prefer a convex mirror as a rear-view mirror in vehicles?
Answer- A convex mirror is preferred as a rear-view mirror in cars and vehicles as it gives a wider field of view, which helps the driver see most of the traffic behind him. Convex mirrors always form an erect, virtual, and diminished image of the objects placed in front of it.
- ScienceClass 10CBSE
Name the mirror that can give an erect and enlarged image of an object.
Answer- The mirror that can give an erect and enlarged image of an object is a Concave Mirror.
- ScienceClass 10CBSE
The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
Answer- Radius of curvature (R) = 20 cm Radius of curvature of the spherical mirror = 2 × Focal length (f) R = 2f f= R/2 = 20 / 2 = 10 Therefore, the focal length of the spherical mirror is 10 cm.
- ScienceClass 10CBSE
Define the principal focus of a concave mirror.
Answer- Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is called the principal focus of the concave mirror.