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Q1. Which type of mirror has a reflecting surface that curves inwards?
A concave mirror has a reflecting surface that curves inward, like the inside of a spoon. This type of mirror converges parallel rays of light to a single point called the focus. It is also known as a converging mirror.
Q2. The focal length of a spherical mirror is the distance between the pole and the _________.
The focal length (f) is defined as the distance between the pole (P) and the focus (F) of a spherical mirror. It is half of the radius of curvature. The focus is the point where parallel rays of light converge (for concave) or appear to diverge from (for convex).
Q3. Which mirror always forms a virtual, erect, and diminished image regardless of object position?
A convex mirror always forms a virtual, erect, and diminished (smaller) image no matter where the object is placed. This is because the reflected rays diverge and only appear to meet behind the mirror. This property makes it useful for rear-view mirrors.
Q4. A concave mirror can form a real and inverted image. When does this happen?
A concave mirror forms a real and inverted image only when the object is placed beyond the focus (F). If the object is between the pole and the focus, the image is virtual and erect. At infinity or beyond C, the image is real and inverted.
Q5. What type of image is formed by a concave mirror when the object is placed between the focus (F) and the pole (P)?
When an object is placed between the focus (F) and the pole (P) of a concave mirror, the image formed is virtual, erect, and magnified. The image appears behind the mirror. This is why concave mirrors are used as shaving and makeup mirrors.
Q6. The image formed by a convex mirror is always __________.
A convex mirror always forms a virtual, erect, and diminished image regardless of the object’s position. The image is formed behind the mirror and cannot be obtained on a screen. This makes it ideal for use in vehicles to provide a wider field of view.
Q7. Which mirror is used as a shaving or makeup mirror?
A concave mirror is used as a shaving or makeup mirror because when the face is placed between the focus and the pole, the mirror produces a virtual, erect, and magnified image. This enlargement helps in seeing fine details clearly.
Q8. The point at the center of the spherical mirror’s surface is called the _________.
The pole (P) is the exact center of the reflecting surface of a spherical mirror. It lies on the principal axis. The centre of curvature (C) is the center of the hollow sphere from which the mirror is made, and the focus (F) is the point where parallel rays meet.
Q9. Where should an object be placed in front of a concave mirror to get an image of the same size?
When an object is placed at the centre of curvature (C) of a concave mirror, 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.
Q10. Which mirror is used as a side-view mirror in vehicles?
Convex mirrors are used as side-view mirrors in vehicles because they provide a wider field of view. Although the images are diminished, the driver can see a larger area behind the vehicle, which helps in safe driving and avoiding accidents.
Q11. For a concave mirror, if the object is at infinity, where is the image formed?
When the object is at infinity, the rays coming from it are parallel. After reflection from a concave mirror, these parallel rays converge at the focus (F). This principle is used in solar cookers where sunlight (from infinity) is concentrated at the focus.
Q12. A convex mirror forms an image that is always __________ than the object.
A convex mirror always forms a diminished (smaller) image compared to the object. This is because the reflected rays diverge and the image appears smaller. This property helps in fitting a larger area into the mirror, providing a wider field of view.
Q13. Which mirror is used by dentists to see an enlarged image of teeth?
Dentists use concave mirrors because they can produce a magnified (enlarged) image when the tooth is placed between the focus and the pole. This allows dentists to see small cavities and details clearly, helping in proper treatment.
Q14. The radius of curvature (R) of a spherical mirror is related to its focal length (f) by __________.
The radius of curvature (R) is twice the focal length (f) for any spherical mirror. So, R = 2f or f = R/2. This relationship is true for both concave and convex mirrors and is a fundamental property of spherical mirrors.
Q15. The image formed by a concave mirror can be projected on a screen only when it is __________.
Only real images can be projected on a screen because real images are formed when light rays actually meet at a point. Virtual images are formed when rays only appear to meet and cannot be captured on a screen. Concave mirrors form real images when the object is beyond the focus.
Q16. Which type of mirror is used in solar cookers?
Solar cookers use concave mirrors to concentrate sunlight at the focus. The parallel rays from the sun converge at the focus, producing intense heat. This heat is used for cooking. Concave mirrors are ideal for this because they are converging mirrors.
Q17. The center of the hollow sphere of which the spherical mirror is a part is called the __________.
The centre of curvature (C) is the center of the imaginary hollow sphere from which the spherical mirror is made. It is located on the principal axis at a distance equal to the radius of curvature from the pole. The pole is the center of the mirror’s surface.
Q18. When an object is placed at the focus (F) of a concave mirror, the image formed is __________.
When an object is placed at the focus of a concave mirror, the reflected rays become parallel to each other. These parallel rays meet only at infinity. This principle is used in searchlights and headlights, where a bulb at the focus gives a parallel beam of light.
Q19. Which mirror is used in shops for security and surveillance?
Convex mirrors are used in shops for security and surveillance because they provide a wider field of view. A single convex mirror can cover a large area, allowing shopkeepers to monitor customers and prevent theft. The diminished image helps see more of the shop at once.
Q20. The reflecting surface of a convex mirror bulges __________.
A convex mirror has a reflecting surface that bulges outward, like the outside of a spoon. This outward curvature causes the mirror to diverge light rays, forming virtual, erect, and diminished images. It is also called a diverging mirror.
Q21. For a concave mirror, an enlarged image is formed when the object is placed __________.
A concave mirror forms an enlarged (magnified) image in two cases: (1) when the object is between F and C, the image is real, inverted, and enlarged; (2) when the object is between F and P, the image is virtual, erect, and enlarged. So both C and D are correct for different types of enlarged images.
Q22. Which mirror is used as a reflector in torchlights?
Concave mirrors are used as reflectors in torchlights, headlights, and searchlights. The light source (bulb) is placed at the focus of the concave mirror. The reflected rays emerge as a parallel beam, directing light in a specific direction over a long distance.
Q23. A virtual image formed by a spherical mirror is always __________.
A virtual image formed by any spherical mirror is always erect (upright). It cannot be obtained on a screen. Concave mirrors form virtual erect images when the object is between F and P, while convex mirrors always form virtual erect images.
Q24. Which mirror is used in headlights of vehicles?
Headlights of vehicles use concave mirrors. The bulb is placed at the focus of the concave mirror, and the reflected rays become parallel, producing a strong beam of light that illuminates the road ahead. This ensures better visibility during night driving.
Q25. The line passing through the centre of curvature and the pole of a mirror is called the __________.
The principal axis is an imaginary straight line that passes through the pole (P) and the centre of curvature (C) of a spherical mirror. All measurements like focal length and radius of curvature are taken along this axis. The focus also lies on this axis.
Q26. Where is the image formed by a convex mirror located?
A convex mirror always forms its image behind the mirror. The image is virtual, erect, and diminished. Since the reflected rays diverge, they appear to come from a point behind the mirror, which is the focus of the convex mirror.
Q27. Which mirror can produce both real and virtual images?
A concave mirror can produce both real and virtual images depending on the position of the object. If the object is beyond the focus, the image is real. If the object is between the focus and the pole, the image is virtual. Plane and convex mirrors always produce virtual images.
Q28. The focal length of a convex mirror is taken as __________.
According to the sign convention, the focal length of a convex mirror is taken as positive because the focus lies behind the mirror. For a concave mirror, the focal length is negative because the focus lies in front of the mirror.
Q29. A concave mirror is also called a __________ mirror.
A concave mirror is called a converging mirror because it converges parallel rays of light to a single point (the focus). In contrast, a convex mirror is called a diverging mirror because it spreads out parallel rays.
Q30. Which mirror is used in blind corner mirrors on roads?
Convex mirrors are used at blind corners on roads because they provide a wider field of view. Drivers can see vehicles coming from around the corner, helping to prevent accidents. The diminished image allows a larger area to be seen.
Q31. When an object is placed between the focus (F) and centre of curvature (C) of a concave mirror, the image is formed __________.
When an object is placed between the focus (F) and the centre of curvature (C) of a concave mirror, the image is formed beyond C. The image is real, inverted, and magnified (larger than the object). This is used in projectors and cameras.
Q32. Which of these is NOT a use of a concave mirror?
Security mirrors use convex mirrors, not concave mirrors. Convex mirrors provide a wider field of view, making them suitable for security and surveillance. Concave mirrors are used for shaving, dental work, and as reflectors in headlights.
Q33. A convex mirror is also called a __________ mirror.
A convex mirror is called a diverging mirror because it diverges (spreads out) parallel rays of light after reflection. The reflected rays appear to come from a point behind the mirror. This is opposite to a concave mirror, which is a converging mirror.
Q34. The image formed by a plane mirror is __________.
A plane mirror always forms a virtual, erect, and same-sized image. The image is formed behind the mirror and cannot be obtained on a screen. It also shows lateral inversion (left-right reversal).
Q35. Which mirror is used in telescopes?
Large concave mirrors are used as the primary mirrors in reflecting telescopes. They gather light from distant stars and planets and focus it to form a real image. This allows astronomers to observe faint celestial objects clearly.
Q36. The focal length of a concave mirror is taken as __________.
According to the sign convention, the focal length of a concave mirror is taken as negative because the focus lies in front of the mirror (on the same side as the incident light). For a convex mirror, the focal length is positive.
Q37. For any spherical mirror, the angle of incidence is __________ the angle of reflection.
The first law of reflection states that for any mirror (plane or spherical), the angle of incidence is always equal to the angle of reflection. Both angles are measured with respect to the normal at the point of incidence.
Q38. Which mirror is used as a rear-view mirror in cars and motorcycles?
Convex mirrors are used as rear-view mirrors in cars and motorcycles because they provide a wider field of view. Although objects appear smaller and farther away, the driver can see a larger area behind the vehicle, which is essential for safe driving.
Q39. When an object is moved from infinity towards the pole of a concave mirror, the size of the image __________.
As an object moves from infinity towards the pole of a concave mirror, the size of the real image gradually increases. At infinity, the image is highly diminished. As the object approaches the centre of curvature, the image grows until it is the same size at C and larger beyond C.
Q40. A real image is always __________.
A real image is always inverted (upside down) and can be obtained on a screen. It is formed when light rays actually meet after reflection. Virtual images, on the other hand, are always erect and cannot be captured on a screen.
Q41. Which mirror is used in solar furnaces?
Solar furnaces use large concave mirrors to concentrate sunlight at the focus. The intense heat generated at the focus can reach very high temperatures, which is used in solar furnaces for melting metals or generating electricity.
Q42. The relation between focal length (f) and radius of curvature (R) for a convex mirror is __________.
For any spherical mirror (whether concave or convex), the focal length (f) is always half of the radius of curvature (R). So, f = R/2. This is a universal relationship for spherical mirrors and does not depend on the type of mirror.
Q43. A diminished, virtual, and erect image is characteristic of which mirror?
A convex mirror always forms a diminished, virtual, and erect image regardless of where the object is placed. This is a unique property of convex mirrors. Concave mirrors form diminished real images only in specific cases.
Q44. Which of these is a use of a convex mirror?
Convex mirrors are used at blind turns on roads to provide a wider field of view. Magnifying glasses use convex lenses, shaving mirrors use concave mirrors, and street light reflectors also use concave mirrors.
Q45. The focal point of a convex mirror is located __________.
The focus of a convex mirror is located behind the mirror because the reflected rays diverge and only appear to meet at a point behind the mirror. This focus is virtual and is located at half the radius of curvature from the pole.
Q46. For a concave mirror, if the object is placed at the centre of curvature (C), the image is formed __________.
When an object is placed at the centre of curvature (C) of a concave mirror, 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 the formation of images by concave mirrors.
Q47. Which mirror is used in floodlights?
Floodlights use concave mirrors to produce a powerful, concentrated beam of light. The light source is placed at the focus, and the concave mirror reflects the light as a parallel beam, illuminating a large area. This is also used in searchlights and sports stadium lighting.
Q48. The image formed by a concave mirror is virtual and erect only when the object is placed __________.
A concave mirror forms a virtual and erect image only when the object is placed between the pole (P) and the focus (F). The image is also magnified (larger). This is the principle behind shaving mirrors and makeup mirrors.
Q49. Which mirror has a wider field of view?
Convex mirrors have the widest field of view among all types of mirrors. Because they bulge outward, they can reflect light from a larger area. This is why they are used in rear-view mirrors, security mirrors, and at blind corners on roads.
Q50. A concave mirror of focal length 10 cm has its radius of curvature equal to __________.
The radius of curvature (R) is twice the focal length (f). Given f = 10 cm, R = 2f = 2 × 10 = 20 cm. This relationship (R = 2f) is true for all spherical mirrors and is a fundamental formula in optics.