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Q1. What is the size of the image when an object is placed at F in front of a concave mirror?
When an object is placed at the focus (F) of a concave mirror, the reflected rays become parallel and meet at infinity. The image formed is real, inverted, and highly enlarged (magnified). This principle is used in searchlights and headlights.
Q2. What is the size of the image when an object is placed between C and F in front of a concave mirror?
When an object is placed between the centre of curvature (C) and the focus (F), the image is formed beyond C. The image is real, inverted, and enlarged (magnified). This is used in projectors and cameras.
Q3. For which position of the object in front of a concave mirror is the image diminished?
When the object is placed beyond the centre of curvature (C), the image is formed between F and C. The image is real, inverted, and diminished (smaller than the object). This is used in cameras to capture distant objects.
Q4. What type of image is formed by a concave mirror when the object is placed between P and F?
When the object is placed between the pole (P) and the focus (F), the image formed is virtual, erect, and enlarged. The image appears behind the mirror. This is why concave mirrors are used as shaving and makeup mirrors.
Q5. What is the nature of the image formed when an object is placed beyond C in front of a concave mirror?
When the object is placed beyond the centre of curvature (C), the image is formed between F and C. The image is real (can be obtained on a screen), inverted, and diminished. This is the principle used in cameras.
Q6. When using a concave mirror, a sharp bright spot of light obtained on paper is actually:
When sunlight (parallel rays) falls on a concave mirror, it converges at the focus. The bright spot on the paper is the real image of the Sun formed at the focus. This demonstrates how concave mirrors concentrate light.
Q7. In the activity with a concave mirror, when might you not get an image on the screen?
When the object is between the pole (P) and the focus (F), the image formed is virtual and behind the mirror. Virtual images cannot be obtained on a screen. Real images (formed when the object is beyond F) can be obtained on a screen.
Q8. Where is the image formed when an object is placed at C in front of a concave mirror?
When the object is placed at the centre of curvature (C), the image is formed at C itself. The image is real, inverted, and of the same size as the object. This is a special case in image formation by concave mirrors.
Q9. In the activity with the concave mirror and candle, where should the candle be placed to get a highly enlarged image?
When the candle (object) is placed at the focus (F) of the concave mirror, the image is formed at infinity and is highly enlarged. However, to get a highly enlarged image on a screen, the object should be placed between F and C for an enlarged real image.
Q10. What is the nature of the image formed by a concave mirror when the object is at the focus?
When the object is placed at the focus (F), the reflected rays become parallel and meet at infinity. The image formed is real, inverted, and highly enlarged (at infinity). This is used in searchlights to produce parallel beams.
Q11. How can the approximate focal length of a concave mirror be determined?
The focal length of a concave mirror can be approximately determined by focusing the image of a distant object (like the Sun or a faraway building) on a sheet of paper. The distance between the mirror and the sharp image gives the focal length.
Q12. What is the nature of the image formed when an object is placed between P and F in front of a concave mirror?
When the object is placed between the pole (P) and the focus (F), the image is virtual, erect, and magnified. The image is formed behind the mirror and cannot be obtained on a screen. This is used in magnifying mirrors.
Q13. Which of the following statements about image formation by concave mirrors is correct?
Concave mirrors can form both real and virtual images depending on where the object is placed. If the object is beyond F, the image is real; if the object is between P and F, the image is virtual. This flexibility makes concave mirrors versatile.
Q14. What is the size of the image when an object is placed at C in front of a concave mirror?
When the object is placed at the centre of curvature (C), the image is formed at C and is of the same size as the object. The image is real and inverted. This is a unique case where the image size equals the object size.
Q15. At the point of incidence on a spherical mirror, what relationship exists between the angle of incidence and angle of reflection?
According to the first law of reflection, the angle of incidence is always equal to the angle of reflection. This law applies to all mirrors, including spherical mirrors. Both angles are measured from the normal at the point of incidence.
Q16. For which position of the object in front of a concave mirror is the image of the same size as the object?
When the object is placed at the centre of curvature (C), the image formed is at C and is of the same size as the object. For all other positions, the image is either enlarged or diminished.
Q17. For which position of the object in front of a concave mirror is a virtual image formed?
A virtual image is formed by a concave mirror only when the object is placed between the pole (P) and the focus (F). In all other positions (beyond F), the image formed is real.
Q18. What does the intersection of at least two reflected rays give in a ray diagram?
In a ray diagram, the intersection point of at least two reflected rays gives the position of the image. If the rays actually meet, the image is real; if they appear to meet, the image is virtual.
Q19. Where is the image formed when an object is placed between P and F in front of a concave mirror?
When the object is placed between the pole (P) and the focus (F), the image is formed behind the mirror. The image is virtual, erect, and enlarged. It cannot be obtained on a screen.
Q20. Which ray, after reflection from a concave mirror, is reflected back along the same path?
A ray passing through the centre of curvature strikes the mirror along the normal (perpendicular to the surface). Therefore, it reflects back along the same path. This is a standard rule used in ray diagrams for concave mirrors.
Q21. A ray incident obliquely to the principal axis towards the pole of a concave mirror is reflected:
Any ray incident obliquely at the pole of a concave mirror is reflected obliquely, following the laws of reflection. The angle of incidence equals the angle of reflection with respect to the normal at the pole.
Q22. Where is the image formed when an object is placed between C and F in front of a concave mirror?
When the object is placed between the centre of curvature (C) and the focus (F), the image is formed beyond C. The image is real, inverted, and enlarged. This is used in projectors to produce enlarged images on screens.
Q23. In ray diagrams for spherical mirrors, how many rays are typically considered for clarity?
In ray diagrams, typically two rays are considered to locate the image. The intersection of these two reflected rays gives the position of the image. Using more than two rays can make the diagram cluttered.
Q24. For which position of the object in front of a concave mirror is the image highly diminished?
When the object is at infinity, the rays are parallel. After reflection from a concave mirror, they converge at the focus. The image formed is real, inverted, and highly diminished (a point image). This is used in solar cookers to concentrate sunlight.
Q25. Where is the image formed when an object is placed at F in front of a concave mirror?
When the object is placed at the focus (F), the reflected rays emerge parallel to each other. These parallel rays meet only at infinity. So, the image is formed at infinity and is highly enlarged.
Q26. What is the size of the image when an object is placed between P and F in front of a concave mirror?
When the object is placed between the pole (P) and the focus (F), the image is virtual, erect, and enlarged (magnified). This is why concave mirrors are used as magnifying mirrors for shaving and makeup.
Q27. Which ray, after reflection from a concave mirror, emerges parallel to the principal axis?
A ray passing through the principal focus (F) of a concave mirror, after reflection, emerges parallel to the principal axis. This is the reverse of the rule that a ray parallel to the principal axis passes through F after reflection.
Q28. For a spherical mirror of small aperture, where does the principal focus F lie?
For a spherical mirror with a small aperture, the principal focus (F) lies exactly midway between the pole (P) and the centre of curvature (C). This means the focal length f = R/2, where R is the radius of curvature.
Q29. Where is the image formed when an object is at infinity in front of a concave mirror?
When the object is at infinity, parallel rays fall on the concave mirror. After reflection, they converge at the focus (F). The image is real, inverted, and highly diminished (a point image). This principle is used in solar cookers.
Q30. Which ray, after reflection from a concave mirror, passes through the principal focus?
A ray of light incident parallel to the principal axis of a concave mirror, after reflection, passes through the principal focus (F). This is one of the standard rules used in ray diagrams for concave mirrors.