Class 10 Science Chapter 9 Practice Question Answers - Light Reflection and Refraction

Clear all your Class 10 doubts with EduRev Join for Free

Join for Free

Fill in the Blanks:
Q1:When light passes from a rarer to a denser medium, it bends _______ the normal.

Ans: towards
Explanation: When light travels from a rarer medium (e.g., air) to a denser medium (e.g., glass), it slows down and bends towards the normal due to the change in speed.

Q2: The point at which the incident ray meets the mirror is called the _______ point.

Ans: incident 

Explanation: The incident point is where the incoming ray of light touches the mirror's surface before reflection occurs.

Q3: The angle between the incident ray and the normal is known as the angle of _______.

Ans: incidence
Explanation: The angle of incidence is the angle formed by the incident ray and the perpendicular line (normal) at the point of incidence.

Q4:The type of mirror used in a magnifying glass is a _______ mirror.

Ans: convex 
Explanation: A convex mirror is curved outward and is used in magnifying glasses because it allows light rays to diverge, creating a larger virtual image.

Q5: The phenomenon responsible for the dispersion of white light into its component colors is called _______.

Ans: dispersion 
Explanation: Dispersion occurs when white light splits into its spectrum of colors (e.g., in a prism) due to different wavelengths of light bending by different amounts.

Short Answer Questions

Q6: Define the term 'refraction' of light.
Ans: Refraction is the bending of light when it passes from one transparent medium to another, due to a change in its speed.

Q7: State Snell's Law.
Ans:  

• Snell's Law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant when a ray of light passes from one medium to another. 
•  Mathematically, it can be written as: n₁ sin α₁ = n₂ sin α₂, where n₁ and n₂ are the refractive indices of the two media, and α₁ and α₂ are the angles of incidence and refraction, respectively. 

Q8: Explain the term 'total internal reflection' of light.
Ans: 

• Total internal reflection occurs when a ray of light traveling in a denser medium strikes the boundary with a rarer medium at an angle greater than the critical angle.
• In such cases, the light is completely reflected back into the denser medium, and no refraction occurs.

• A rainbow forms when sunlight passes through raindrops in the atmosphere. The process involves: 
• Refraction: Light enters a raindrop and bends as it slows down, separating into its component colors. 
• Internal Reflection: The light reflects off the inner surface of the raindrop. 
• Refraction Again: As the light exits the raindrop, it bends again, further separating the colors. 
• Dispersion: This separation of light into colors creates the spectrum, with red on the outer edge and violet on the inner edge. 
•  A rainbow is seen when the observer's back is to the sun and the light exits raindrops at a specific angle. 

Q15: How does the human eye focus on near and distant objects?
Ans:

•  The human eye adjusts its focus using a process called accommodation. 
• When focusing on a near object, the ciliary muscles contract, causing the lens to become more convex, which increases its refractive power.
• For distant objects, the ciliary muscles relax, allowing the lens to become flatter, reducing its refractive power.
•  This adjustment ensures that clear images are formed on the retina for objects at varying distances.