Class 10 - Physics - Light - Numerical and Questions #eduvictors #class10-physics

Class 10 - Physics - Light - Numerical and Questions

(See also at set 1)

Q1: When an object is placed at a distance of 60 cm from a convex mirror, the magnification produced is 1/2.
Where should the object be placed to get a magnification of 1/3?

Answer:

Q2: When an object is kept at a distance of 60cm from a concave mirror, the magnification is 1/2. Where should the object be placed to get a magnification of 1/3?

Answer: (Hint: steps are the same as in the above question, except it is a concave mirror, m = -1/2. Compute f in the first case i.e. f = -20 cm and the compute u in case II i.e. u = 80 cm)

Q3(CBSE Board): A concave lens made of material of refractive index (n₁) is kept in a medium of refractive index (n₂). A parallel beam of light is incident on the lens. Complete the path of the rays of light emerging from a concave lens if: 

(a) n₁ > n₂      

(b) n₁ = n₂ 

(c) n₁ < n₂

Answer:

CBSE Class 10- Chapter 11 - Human Eye and the Colourful World (Very short Q & A)

Human Eye and the Colourful World

Very Short Questions and Answers

Q1: Name a light sensitive part of the eye where image of an object is formed.
Answer: Retina

Q2: Name the muscle responsible for bringing change in the focal length of the eye lens ?
Answer: Ciliary Muscles

Q3: Name one defect of vision which cannot be corrected by any type of spectacle lenses ?
Answer: Cataract

Q4: What is the nature of image formed on the retina of the eye ?
Answer: Real and inverted image.

Q5: Name the transparent membrane through which light enters the eye.
Answer: Cornea

Q6: What type of signals are generated & sent to the brain by light sensitive cells of retina?
Answer: Elctro-chemical Nerve signals are generated by rods and cones (photo sensitive cells of retina) and are sent to brain by optic nerve.

Class 10 - Light Reflection and Refraction (Short Q & A)

Light Reflection and Refraction 

(Short Q & A)

Q1: In which type of lens linear magnification is always less then one?

Answer: Concave Lens always has linear magnification less than one, because it always gives diminished images.

Q2: John obtained a magnification of 1 with concave mirror of focal length 10cm. What is the object distance from mirror?

Answer: m = 1. Therefore u = v. Apply it in mirror formula, you will get v = 20 cm. 

Q3: Which mirror has a wider field of view?

Answer: convex mirrors have wilder field view, that's why these are used as rear view-mirrors in vehicles. 

Q4: Which is optically denser out of the two mediums M1 and M2 having n = 1.71 and 1.36
respectively.

Answer: M1 (it has higher value of refractive index).

Q5: Identify a mirror having focal length –15cm

Answer: concave mirror (see -ve sign of focal length).

Class 10 - Light MCQ - Quiz

Light (Quiz)

MCQs
1. The line perpendicular to the reflective surface is the __________.
    a. normal
    b. line of refraction
    c. line of incidence
    d. line of reflection

2. Your image in a bathroom mirror results from __________.
   a.  diffuse reflection
   b. specular refraction
   c. specular reflection
   d. diffuse refraction

3. How does light normally travel?
    a.  in concentric circles
    b.  in a straight line
    c. always toward a dark area
    d. in a curved line

class 10 - Numericals on Light Reflection and Refraction

Numerical Problem on Light Reflection and Refraction

(More numerical and questions at this page)
Q1: How fast does the light travel in a glass of refractive index 1.5?

Answer:
  By Snell's law, refractive index (n) is the ratio of i.e.

 






Q2:When a bright object is placed 10 cm away from a concave mirror, its real image is formed at a distance 40cm from the mirror. What is the focal length of the mirror?

Answer:
     







Q3: If the angle of incidence of a ray of light falling on the glass surface is 30° and the angle of refraction is 19°. what is the refractive index of glass?

Ans:
      angle of incidence  i = 30°
      angle of refraction  r = 19°
      refractive index   n = sin i/sin r  = sin 30/sin 19
                                  n = .5/.3256 = 1.535               ....(ans)

Q4: If a child crawls towards a mirror at a rate of 0.20 m/s, then at what speed will the child and her image come nearby to each other?

Ans: In 1 sec, the child moves towards the mirror by a distance of 0.20 meters. In the same second, her image also moves 0.20m closer.
Therefore, the child and her image comes closer to each other by 0.40m per second.

class 10 - Notes on Light and Reflection

Notes on Light and Reflection

1. Light is a form of energy. Since energy cannot be seen, we see objects in light.

2. A ray of light is a straight line which represents the path of traveling light. A collection of light rays is called a beam of light.

3. Q: How do we see objects?
   Ans: The visual ability of humans is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at.

4. Luminous objects are objects that generate their own light. e.g. firefly, the sun.

5. Illuminated objects are objects that are capable of reflecting light to our eyes. e.g. the moon

6. A ray of light that falls on a surface is called incident ray.

7. The light that is sent back by the reflecting surface is called reflection.

8. The ray that is sent back by the reflecting surface is called the reflected ray.

9. When light falls on a body, it may be absorbed, may be transmitted or light may come back to the same medium.

10. Laws of Reflection (watch  the you tube video):
   

     a. First law of reflection: The incident ray, the normal to the surface at the point of incidence and the reflected ray, all lie in the same plane.

      b. Second law of reflection: The angle of incidence is equal to the angle of reflection.