Class 7 Science Chapter 13 Important Question Answers - Light

Very Short Answer Type Questions

Q1: What is the characteristic path of light?
Ans: The path of light is always straight and never curved.

Q2: Define the term "reflection of light."
Ans: Reflection of light is the bouncing of light by any smooth surface, such as a mirror.

Q3: What is the impression of an object formed in a mirror called?
Ans: The impression of an object formed in a mirror is called the image of the object.

Q4: Explain why we use mirrors in interior decoration to make rooms appear brighter and bigger.
Ans: Placing mirrors near lights, chandeliers, and table lamps reflects light over a larger area, making rooms appear brighter. The concept that images in a mirror are located at the same distance behind the mirror as the object in front of it is used to make rooms appear bigger.

Q5: What are virtual images?
Ans: Virtual images are images that cannot be captured on a screen or surface.

Q6: Describe the characteristics of an image formed by a plane mirror.
Ans: An image formed by a plane mirror is the same size as the object, left-right inversed, erect, virtual, and formed at the same distance behind the mirror as the object in front of it.

Q7: What types of spherical mirrors exist, and how do they differ?
Ans: There are two types of spherical mirrors: concave mirrors and convex mirrors. Concave mirrors have a curved inward reflecting surface, while convex mirrors have a curved outward reflecting surface.

Q8: Explain the difference between a concave mirror and a convex mirror.
Ans: A concave mirror is used to magnify objects, and it forms virtual, erect, and magnified images when the object is placed at different distances. In contrast, a convex mirror forms virtual, erect, and diminished images and is often used in applications like rear-view mirrors in vehicles.

Q9: What are real images, and where are they captured?
Ans: Real images are images that can be captured on a screen or surface. For example, in a camera, images are real and can be captured on the negative.

Q10: What is the purpose of red oxide coating on transparent spherical surfaces?
Ans: Red oxide coating on transparent spherical surfaces helps to differentiate between concave and convex mirrors. If the concave surface is silvered and coated with red oxide, it acts as a convex mirror, and if the convex surface is silvered and coated with red oxide, it acts as a concave mirror.

Short Answer Type Questions

Q11: Explain the concept of the path of light and its behavior.
Ans: The path of light is always straight and never curved. It doesn't bend unless it encounters a reflecting surface. For example, light from a torch or vehicle headlights travels in straight lines until it reflects off a surface.

Q12: Define and describe the reflection of light. Provide an example.
Ans: Reflection of light refers to the bouncing of light by a smooth surface like a mirror. When light strikes a mirror, it reflects off the mirror's surface. For example, when you see your own reflection in a mirror, it is due to the reflection of light.

Q13: What are the characteristics of an image formed by a plane mirror?
Ans: An image formed by a plane mirror is the same size as the object, left-right inversed, erect, virtual, and formed at the same distance behind the mirror as the object is in front of it. These properties make it ideal for reflection without distortion.

Q14: Differentiate between concave and convex mirrors and provide examples of their applications.
Ans: Concave mirrors are used to magnify objects and can form both virtual and real images. They are used in applications such as dental mirrors, flashlights, and car headlights. Convex mirrors, on the other hand, form virtual, erect, and diminished images. They are used in rear-view mirrors in vehicles, parking lots, and security applications.

Q15: Explain the concept of virtual images and provide an example.
Ans: Virtual images are images that cannot be captured on a screen or surface. For example, the image seen in a plane mirror is virtual because it cannot be touched or captured but appears to be behind the mirror.

Q16: Describe the dispersion of light through a prism and what causes it.
Ans: Dispersion of light through a prism occurs when a narrow beam of sunlight passes through a prism. Different component colors of white light bend differently as they pass through the prism due to the phenomenon of refraction, creating a spectrum of colors.

Q17: What is a rainbow, and how is it formed?
Ans: A rainbow is a band of colors extending from violet to red, formed by the refraction and reflection of the sun's rays through raindrops. It appears when it is raining in one part of the sky and sunny in another. The center of the rainbow's arc is always directed away from the sun.

Q18: Explain the concept of concave and convex lenses, including their properties and applications.
Ans: Concave lenses are thinner at the center than at the edges, and they diverge light rays. They are used to correct conditions like nearsightedness. Convex lenses are thicker at the center and converge light rays, making them ideal for magnifying objects. They are used in magnifying glasses, cameras, microscopes, and telescopes.

Q19: Describe the applications of lenses and provide examples.
Ans: Lenses have various applications, such as magnifying glasses for reading, cameras for photography, microscopes for scientific observation, and telescopes for stargazing. They are also used in devices like binoculars and projectors.

Q20: Why is the red oxide coating applied to transparent spherical surfaces, and how does it affect their functionality?
Ans: Red oxide coating is applied to differentiate between concave and convex mirrors made from transparent spherical surfaces. When the concave surface is silvered and coated with red oxide, it acts as a convex mirror, and vice versa. This helps in identifying the type of mirror and its specific function.