Master the important concepts of Light through this TNPSC Physics – Light Quiz 2. Test your knowledge of reflection, refraction, laws of reflection, image formation by mirrors and lenses, refractive index, and real-life applications. Each question is designed to match the TNPSC exam pattern and includes clear explanations to strengthen your understanding and improve your score.
Next → TNPSC Physics – Light (Reflection and Refraction) Quiz 3
TNPSC Physics – Light Quiz 2 – Detailed Explanation
Every explanation in this quiz goes beyond the correct answer by highlighting the scientific principle behind it. You’ll understand how light behaves through reflection and refraction, where these concepts appear in everyday life, and the types of questions commonly asked in TNPSC exams. Reviewing these explanations will help you avoid common mistakes and strengthen your conceptual understanding.
1. A ray of light passes through the centre of curvature of a concave mirror. After reflection, the ray will:
A ray passing through the centre of curvature strikes the concave mirror along the normal (perpendicular) to its surface. Since the angle of incidence is zero, the reflected ray retraces its original path.
Key Points:
- The centre of curvature is represented by C.
- A ray passing through C is reflected back along the same path.
- This is one of the principal ray rules used in image formation.
Real-Life Example:
This principle is used while drawing ray diagrams to determine image formation by concave mirrors.
Correct Answer: B. Retrace its original path
2. A ray of light travelling parallel to the principal axis of a concave mirror, after reflection, passes through the:
A ray travelling parallel to the principal axis of a concave mirror is reflected through its principal focus. This is one of the fundamental rules of reflection used in ray diagrams.
Key Points:
- Parallel rays converge at the principal focus (F).
- A concave mirror is also called a converging mirror.
- This property is used to form real images.
Real-Life Example:
Solar cookers use concave mirrors to focus sunlight and produce high temperatures.
Correct Answer: C. Principal Focus
3. The distance between the pole and the principal focus of a spherical mirror is known as:
The distance from the pole (P) to the principal focus (F) is called the focal length. It determines how strongly a mirror converges or diverges light rays.
Key Points:
- Focal length is represented by f.
- It is measured along the principal axis.
- For spherical mirrors, Radius of Curvature (R) = 2 × Focal Length (f).
Real-Life Example:
Mirrors with different focal lengths are used in headlights, telescopes, and shaving mirrors.
Correct Answer: D. Focal Length
4. In a spherical mirror, the centre of the reflecting surface is called the:
The pole is the midpoint of the reflecting surface of a spherical mirror. It serves as the reference point for measuring focal length and other mirror distances.
Key Points:
- The pole is represented by P.
- It lies on the principal axis.
- All mirror measurements are taken from the pole.
Real-Life Example:
The pole acts as the reference point when drawing mirror ray diagrams.
Correct Answer: B. Pole
5. The line joining the pole and the centre of curvature of a spherical mirror is known as the:
The straight line passing through the pole and the centre of curvature is called the principal axis. It is the reference line for studying reflection and image formation.
Key Points:
- The principal axis passes through P and C.
- The principal focus also lies on the principal axis.
- Ray diagrams are drawn with respect to this axis.
Real-Life Example:
The principal axis is used in designing optical instruments such as telescopes and reflecting mirrors.
Correct Answer: B. Principal Axis
6. Which mirror can form both real and virtual images depending on the object’s position?
A concave mirror can produce different types of images based on the object’s position relative to its principal focus. It forms real and inverted images when the object is beyond the focus, and a virtual, erect, and magnified image when the object is placed between the pole and the principal focus.
Key Points:
- Only a concave mirror can form both real and virtual images.
- The nature of the image depends on the object’s position.
- Convex and plane mirrors always form virtual images.
Real-Life Example:
Concave mirrors are used as shaving and makeup mirrors because they produce a magnified virtual image when the face is close to the mirror.
Correct Answer: C. Concave Mirror
7. The radius of curvature of a spherical mirror is equal to:
The radius of curvature is the distance between the pole and the centre of curvature of a spherical mirror. For all spherical mirrors, the radius of curvature is twice the focal length, expressed as R = 2f.
Key Points:
- Radius of curvature is represented by R.
- Focal length is represented by f.
- The relationship is R = 2f.
Real-Life Example:
This relationship is used in designing optical instruments such as reflecting telescopes and vehicle headlights.
Correct Answer: B. Twice the Focal Length
8. Which mirror is best suited for concentrating sunlight at a single point?
A concave mirror reflects parallel rays of sunlight and converges them at its principal focus. This concentration of light produces high temperatures, making concave mirrors useful in heating applications.
Key Points:
- A concave mirror is a converging mirror.
- Parallel rays meet at the principal focus.
- Concentrated light produces intense heat.
Real-Life Example:
Solar cookers and solar furnaces use concave mirrors to concentrate sunlight for cooking and generating heat.
Correct Answer: C. Concave Mirror
9. Reflection from a smooth and polished surface is called:
A smooth and polished surface reflects light rays in a single direction, producing a clear and sharp image. This type of reflection is known as regular or specular reflection.
Key Points:
- Occurs on smooth, polished surfaces.
- Reflected rays remain parallel.
- Produces a clear and distinct image.
Real-Life Example:
A plane mirror reflects light regularly, allowing us to see a clear image of ourselves.
Correct Answer: B. Regular Reflection
10. Reflection from a rough surface results in:
When light falls on a rough surface, the reflected rays scatter in different directions because the surface is uneven. This phenomenon is called diffuse reflection and does not produce a clear image.
Key Points:
- Occurs on rough or uneven surfaces.
- Reflected rays scatter in many directions.
- No distinct image is formed.
Real-Life Example:
Walls, paper, and roads exhibit diffuse reflection, enabling objects to be visible from different viewing angles.
Correct Answer: C. Diffuse Reflection
11. A convex mirror always produces an image that is:
A convex mirror always forms a virtual, erect, and diminished image regardless of the object’s position. Since it diverges reflected light rays, the image appears to be formed behind the mirror.
Key Points:
- A convex mirror always forms a virtual image.
- The image is erect and smaller than the object.
- It provides a wider field of view than other mirrors.
Real-Life Example:
Convex mirrors are used as rear-view mirrors in vehicles to help drivers see a larger area behind them.
Correct Answer: C. Virtual, Erect and Diminished
12. Which mirror is commonly used in solar cookers and solar furnaces?
Concave mirrors converge parallel rays of sunlight at the principal focus, producing high temperatures. This ability makes them suitable for applications that require concentrated solar energy.
Key Points:
- A concave mirror focuses sunlight at one point.
- Concentrated light produces intense heat.
- It is widely used in solar heating applications.
Real-Life Example:
Solar cookers and solar furnaces use concave mirrors to generate heat for cooking and industrial purposes.
Correct Answer: C. Concave Mirror
13. Which of the following remains unchanged during reflection of light?
During reflection, light remains in the same medium, so its speed and wavelength do not change. Only the direction of propagation changes according to the laws of reflection.
Key Points:
- Reflection occurs without changing the medium.
- The speed of light remains constant.
- Only the direction of the reflected ray changes.
Real-Life Example:
When light reflects from a mirror, it changes direction but continues to travel at the same speed in air.
Correct Answer: B. Speed of Light
14. Which mirror is most suitable for security surveillance in shops and parking areas?
A convex mirror provides a wide field of view by diverging reflected light rays. This allows a larger area to be observed, making it ideal for surveillance and traffic safety.
Key Points:
- A convex mirror offers a wide field of view.
- It always forms a virtual, erect, and diminished image.
- It helps reduce blind spots.
Real-Life Example:
Convex mirrors are installed in shopping malls, parking lots, and road intersections to improve visibility and safety.
Correct Answer: C. Convex Mirror
15. The image formed by a plane mirror is always:
A plane mirror always forms a virtual, erect image that is the same size as the object. The image appears to be behind the mirror at the same distance as the object is in front of it and exhibits lateral inversion.
Key Points:
- The image is always virtual and erect.
- The image is equal in size to the object.
- The image is laterally inverted and formed at the same distance behind the mirror.
Real-Life Example:
Bathroom and dressing mirrors are plane mirrors because they produce an upright image of the same size.
Correct Answer: B. Virtual, Erect and of the Same Size
16. A ray passing through the principal focus of a concave mirror is reflected:
A ray passing through the principal focus of a concave mirror is reflected parallel to the principal axis. This is one of the principal ray rules used to locate images in ray diagrams.
Key Points:
- A ray through the principal focus becomes parallel after reflection.
- This rule is applicable only to concave mirrors.
- It is commonly used in image construction.
Real-Life Example:
Vehicle headlights use this principle by placing the light source at the principal focus to produce a parallel beam of light.
Correct Answer: B. Parallel to the Principal Axis
17. The principal focus of a convex mirror is located:
A convex mirror causes reflected rays to diverge, so they appear to originate from a point behind the mirror. This point is called the virtual principal focus.
Key Points:
- The principal focus of a convex mirror is virtual.
- It is located behind the mirror.
- Reflected rays diverge after reflection.
Real-Life Example:
Rear-view mirrors in vehicles use convex mirrors, where the image appears to form behind the mirror.
Correct Answer: B. Behind the Mirror
18. The reflecting surface of a convex mirror is:
A convex mirror has its reflecting surface curved outward. This outward curvature causes light rays to diverge after reflection, producing a wide field of view.
Key Points:
- The reflecting surface bulges outward.
- A convex mirror is also called a diverging mirror.
- It always forms virtual, erect, and diminished images.
Real-Life Example:
Convex mirrors are commonly installed at road bends and parking areas to improve visibility.
Correct Answer: B. Curved Outward
19. Which mirror is capable of producing a highly magnified image when the object is placed between the pole and the focus?
When an object is placed between the pole and the principal focus of a concave mirror, the reflected rays appear to meet behind the mirror. As a result, the mirror forms a virtual, erect, and magnified image.
Key Points:
- Only a concave mirror can produce a magnified virtual image.
- The object must be placed between the pole and the principal focus.
- The image formed is virtual, erect, and enlarged.
Real-Life Example:
Dentists and makeup artists use concave mirrors to obtain a larger and clearer view of teeth or facial features.
Correct Answer: C. Concave Mirror
20. The laws of reflection are valid for:
The laws of reflection apply to all reflecting surfaces, whether plane, curved, smooth, or rough. At every point on a reflecting surface, the angle of incidence is equal to the angle of reflection, and the incident ray, reflected ray, and normal lie in the same plane.
Key Points:
- The angle of incidence equals the angle of reflection.
- The incident ray, reflected ray, and normal lie in the same plane.
- These laws are valid for all reflecting surfaces.
Real-Life Example:
The laws of reflection explain image formation in mirrors and are used in optical instruments such as periscopes, telescopes, and vehicle mirrors.
Correct Answer: D. All Reflecting Surfaces
Final Revision – TNPSC Physics: Light (Reflection & Mirrors)
Revise these key points before the exam to quickly remember the important concepts of reflection and spherical mirrors:
- A ray passing through the centre of curvature (C) retraces its original path after reflection.
- A ray parallel to the principal axis of a concave mirror passes through the principal focus (F) after reflection.
- A ray passing through the principal focus (F) of a concave mirror is reflected parallel to the principal axis.
- Pole (P) is the midpoint of the reflecting surface.
- Principal Axis is the straight line joining the Pole (P) and the Centre of Curvature (C).
- Focal Length (f) is the distance between the Pole (P) and the Principal Focus (F).
- Radius of Curvature (R) = 2 × Focal Length (f).
- Concave Mirror (Converging Mirror):
- Can form real or virtual images.
- Used in solar cookers, shaving mirrors, dentist mirrors, and vehicle headlights.
- Convex Mirror (Diverging Mirror):
- Always forms a virtual, erect, and diminished image.
- Provides a wide field of view.
- Used as rear-view mirrors and security mirrors.
- Plane Mirror always forms a virtual, erect image of the same size with lateral inversion.
- Regular Reflection occurs from smooth, polished surfaces and produces a clear image.
- Diffuse Reflection occurs from rough surfaces, scattering light in different directions.
- During reflection, the speed of light remains unchanged because light continues to travel in the same medium.
- Laws of Reflection:
- Angle of incidence = Angle of reflection (∠i = ∠r).
- Incident ray, reflected ray, and normal lie in the same plane.
- These laws are valid for all reflecting surfaces.
Quick Memory Tricks
- C → Same Path (Ray through Centre of Curvature returns on the same path.)
- Parallel → Focus (Concave mirror) , Focus → Parallel (Concave mirror)
- R = 2f
- Concave = Converging = Can form Real & Virtual Images
- Convex = Diverging = Wide View = Always Virtual
- Plane Mirror = Same Size + Lateral Inversion
- Smooth Surface → Regular Reflection
- Rough Surface → Diffuse Reflection
- Reflection changes direction, not speed.
Further Reading
Build a stronger understanding of reflection of light, spherical mirrors, principal focus, focal length, image formation, and the laws of reflection by reading NCERT Class 10 Science – Chapter 9: Light – Reflection and Refraction. The chapter explains the concepts with clear ray diagrams, formulas, and practical applications that are frequently tested in TNPSC and other competitive examinations.
Authority Source:
NCERT Class 10 Science – Chapter 9: Light – Reflection and Refraction (PDF)
