Very Short Q & A :
Q1: Give an example to show that the path of light is always straight and never curved.
Ans: Light emitted by torchlight and light emitted from the headlights of a vehicle
Q2: The bouncing of light by any smooth surface, like a mirror, is called__________________.
Ans: Reflection of light.
Q3: What is the image of an object?
Ans: Due to the reflection of light, the impression of an object formed in a mirror is called the image of the object.
Q4: As the distance of the object from the mirror increases, the distance of the image also increases. True/ False.
Q5: Placing a mirror near lights, and table lamps reflect the light over a larger area and make the room appear brighter. True/ False.
Q6: Images that cannot be captured on a screen are called __________________.
Ans: Virtual images.
Q7: Ravi is looking in a mirror; his right hand will appear to be at ____________ in its image in the mirror.
Ans: Left side
Q8: Why the word ‘AMBULANCE’ is painted left-right inversed on the vehicle?
Ans: So that when the driver of a vehicle in front looks into his rear - view mirror, can read ambulance written on it quickly and give way to it.
Q9: The image formed by a plane mirror is
Ans: (4) All of the above.
Q10: State the principle used in creating a mirror image.
Ans: Principle of reflection
Q11: Name the mirror having a curved reflecting surface.
Ans: Spherical mirror
Q12: Name the two types of spherical mirror.
Ans: Concave mirror and convex mirror.
Q13: State uses of the concave mirror.
Ans: Concave mirrors are used by dentists to obtain a magnified image of the teeth. They are also used in solar heaters or solar concentrators, and as reflectors in flashlights, and headlights of cars and scooters.
Q14: State uses of the convex mirror.
Ans: Convex mirror are used as reflectors at sharp turns and tricky or ‘blind’ corners and in parking lots, and as rear-view mirrors in cars and on motorcycles.
Q15: What is a virtual image?
Ans: The image formed by a plane mirror cannot be captured on a screen, and is called a virtual image.
Q16: What is a real image?
Ans: Images that can be captured on a screen are known as real images.
Q17: Give an example of a real image.
Ans: In a camera, images are real and can be captured on the negative, which acts as a screen.
Q18: In an opaque spherical surface, the silvered surface acts as a mirror. True/ False.
Q19: What happens when light rays are incident on a concave lens?
Ans: When light rays are incident on a concave lens, they bend outwards or diverge.
Q20: What is the name for the concave lens?
Ans: Diverging lens
Q21: What kind of image is formed by the concave lens?
Ans: Upright, virtual and smaller than the object.
Q22: Name an object made from the concave lens.
Ans : Peep holes contain concave lenses.
Q23: A convex lens converges light rays. Therefore, it is also called a ___________________.
Ans: Converging lens
Q24: What kind of image is formed by the convex lens?
Ans: Virtual, erect and magnified.
Q25: State various applications of lenses.
Ans: Lenses are used in magnifying glasses, peepholes, cameras, bioscopes, binoculars, telescopes, microscopes, and projectors.
Q26: A refracting telescope uses a:
Ans: (4) Both 1 and 2.
Q27: How is rainbow formed in the sky?
Ans: A rainbow is formed by the refraction and reflection of the sun’s rays through raindrops.
Q28: When does rainbow appear in the sky?
Ans: When it is raining in one part of the sky and sunny in another, a rainbow appears.
Q29: Although sunlight appears white, it is composed of _________________colours.
Q30: The colors in a rainbow are not the colors of sunlight. True/ False.
Q31: An image formed by a______________mirror is always of the same size as that of the object.
Q32: A concave mirror always forms a real image. True/ False.
Q33: Which type of lens forms always a virtual image?
Ans: A concave lens always forms a virtual, erect and smaller image than the object.
Q34: What is the focal length of a plane mirror?
Q35: State the relation between the radius of curvature and focal length of spherical mirrors.
Radius of curvature = 2 * focal length.
R = 2f.
Q36: Out of convex mirror and the concave mirror, whose focus is situated behind the mirror?
Ans: The focus of convex mirror is situated behind it.