Concave Mirror Practical | Finding Focal Length Using Optical Bench (CBSE Class 12) скачать в хорошем качестве

Concave Mirror Practical | Finding Focal Length Using Optical Bench (CBSE Class 12)

🔥 MOST IMPORTANT VIVA QUESTIONS (HIGH PROBABILITY) 1️⃣ What is a concave mirror? Answer: A concave mirror is a spherical mirror whose reflecting surface is curved inward, towards the center of curvature. 2️⃣ What is the focal length of a concave mirror? Answer: The focal length is the distance between the pole of the mirror and its principal focus. 3️⃣ What is the relation between focal length and radius of curvature? Answer: 4️⃣ Why is an optical bench used in this experiment? Answer: An optical bench is used to align all components (object, mirror, and screen) in a straight line and to measure distances accurately. 5️⃣ Why do we use a concave mirror in this experiment? Answer: Because a concave mirror can form a real and inverted image which can be obtained on a screen. 6️⃣ Why is the image inverted in this experiment? Answer: Because the image formed by a concave mirror for an object placed beyond the focal point is real and inverted. 7️⃣ What kind of image is formed when the object is placed beyond the centre of curvature? Answer: A real, inverted, and diminished image is formed between the focus and the centre of curvature. 8️⃣ What is the mirror formula? Answer: 9️⃣ What sign convention is used? Answer: The New Cartesian sign convention is used. 🔟 Why is the focal length taken as negative for a concave mirror? Answer: Because the principal focus lies on the left side of the mirror (negative direction). ⚠️ VERY COMMON TRICK QUESTIONS (Examiner favourite) 11️⃣ Why should the mirror be vertical? Answer: To avoid error due to improper alignment of the image. 12️⃣ Why do we use a distant object in some methods? Answer: Because rays coming from a distant object are nearly parallel and converge at the focus. 13️⃣ What is parallax? Answer: Parallax is the apparent shift in position of an object when viewed from different angles. 14️⃣ How do you remove parallax? Answer: By adjusting the position of the screen until there is no relative motion between image and reference point. 15️⃣ What is the unit of focal length? Answer: Centimetre (cm) or metre (m). 🧠 THEORY + CONCEPT BASED (SHORT QUESTIONS) 16️⃣ Can a concave mirror form a virtual image? Answer: Yes, when the object is placed between the pole and the focus. 17️⃣ Is the focal length constant? Answer: Yes, for a given mirror, focal length remains constant. 18️⃣Why is a small aperture used? Answer: To obtain a sharp and well-defined image. 20️⃣ What are possible sources of error in this experiment? Answer: Improper alignment Least count error Parallax error Dust on mirror surface 🎯 ONE-LINE QUESTIONS (Rapid Fire) Nature of image formed? → Real and inverted Mirror used? → Concave mirror Method used? → Optical bench method Main formula? → Mirror formula ⚠️ TOP 20 TRAP QUESTIONS (WITH ANSWERS) 1️⃣ Can focal length of a concave mirror be positive? Answer: No, focal length of a concave mirror is always negative. 2️⃣ Does focal length change if mirror is shifted on the optical bench? Answer: No, focal length remains the same. 3️⃣ Can a concave mirror form an erect image? Answer: Yes, when object is placed between pole and focus. 4️⃣ Why image cannot be obtained on screen when object is between F and P? Answer: Because image formed is virtual. 5️⃣ Is mirror formula valid for virtual images? Answer: Yes, mirror formula is always valid. 6️⃣ If object is placed at focus, where is the image formed? Answer: At infinity. 7️⃣ Can focal length be zero? Answer: No, focal length can never be zero. 8️⃣Why is object distance taken negative? Amwer:since object is in left. 9️⃣ Can we use a convex mirror for this experiment? Answer:No, because convex mirror forms only virtual images. 🔟 What happens to focal length if mirror is broken? Answer:Focal length remains same for each piece. 11️⃣ Why do we take multiple readings of u and v? Answer: To reduce experimental error. 12️⃣ Does size of mirror affect focal length? Answer: No, focal length depends only on curvature. 13️⃣ Why do we use small aperture? Answer: To get a sharp image. 14️⃣ Is magnification positive or negative here? Answer: Negative, because image is inverted. 15️⃣ If u = v, what is the position of object? Answer: At centre of curvature (2f). 16️⃣ Can focal length change due to temperature? Answer: No (for practical purposes). 17️⃣ Why is screen placed on same side as object? Answer: Because image is real and formed in front of mirror. 18️⃣ Can focal length be measured using only one reading? Answer: No, multiple readings are required. 19️⃣ Why is mirror cleaned before experiment? Answer: To avoid scattering of light. 20️⃣ If sign convention is ignored, what happens? Answer: Result will be incorrect. 🔥 SUPER-TRAP QUESTION (Examiner smile wala 😄) Q: If concave mirror is immersed in water, what happens to focal length? Answer: Focal length remains unchanged. #PhysicsPractical #ConcaveMirror #FocalLength #OpticalBench #Class12Physics #CBSEPractical #PhysicsExperiment #BoardExam2025 #PracticalPhysics #SciencePractical