Concave Mirror Experiment Viva Questions – Finding Image Distance and Focal Length
Concave Mirror Experiment Viva Questions – Finding Image Distance and Focal Length
Concave Mirror – Viva Questions
A. Basic Concepts
Q1. What is a concave mirror?
Answer: A concave mirror has an inwardly curved reflecting surface; therefore, it converges light rays.
Q2. What types of images does a concave mirror form?
Answer: A concave mirror forms real as well as virtual images; hence, it has wide applications.
Q3. What is the principal axis of a mirror?
Answer: The principal axis passes through the pole and centre of curvature; therefore, it serves as the reference line.
B. Conceptual Understanding
Q4. What do you mean by focal length of a concave mirror?
Answer: The focal length equals the distance between the pole and principal focus; thus, it defines the mirror’s strength.
Q5. Why does a concave mirror converge parallel rays?
Answer: Because its surface curves inward, it reflects rays toward a common point; hence, convergence occurs.
Q6. How does image distance change when object distance decreases?
Answer: As the object moves closer, the image distance increases; therefore, the image shifts farther away.
C. Formula and Sign Convention
Q7. State the mirror formula.
Answer: The mirror formula is 1/f = 1/v + 1/u; therefore, it relates object distance, image distance, and focal length.
Q8. Which sign convention do you use for mirrors?
Answer: We use the Cartesian sign convention; hence, distances measured opposite to incident light remain negative.
Q9. Does focal length change with object position?
Answer: No, focal length remains constant; therefore, it depends only on mirror curvature.
D. Image Formation
Q10. Where does the image form when the object lies beyond the centre of curvature?
Answer: The image forms between the focus and centre of curvature; consequently, it appears diminished.
Q11. What is the nature of image formed when the object lies at infinity?
Answer: The image forms at the focus; thus, it becomes real and highly diminished.
Q12. Why cannot a convex mirror produce a real image on a screen?
Answer: Because a convex mirror diverges rays, they never meet; hence, a real image does not form.
E. Accuracy and Observation
Q13. Why should you take multiple readings?
Answer: Multiple readings reduce random errors; therefore, they improve accuracy.
Q14. Why should the image appear sharp on the screen?
Answer: Sharp images give correct distance values; hence, calculations become reliable.
F. Errors and Precautions
Q15. What error arises due to improper alignment?
Answer: Improper alignment causes incorrect distance measurement; therefore, results become inaccurate.
Q16. Why must you avoid parallax?
Answer: Parallax shifts the apparent position of readings; hence, it leads to wrong values.
G. Applications
Q17. Where do we commonly use concave mirrors?
Answer: We use concave mirrors in shaving mirrors and headlights; therefore, they serve both magnification and focusing.
Q18. Why do vehicle headlights use concave mirrors?
Answer: Because concave mirrors produce parallel beams; consequently, light travels farther.
Final Understanding
Q19. What key relationship does this study establish?
Answer: It establishes the relationship between u, v, and f; thus, it supports the mirror formula.
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