Case 1: A student focuses the image of a candle flame on a white screen using a convex lens.
He noted down the image distance (v) for different object distances (u) and plotted a graph between v and u.
- When u = infinity, what is the value of v?
- What is the nature of the graph between u and v? (Hyperbola/Straight Line)
- If he places the candle at a distance equal to focal length, where will the image form?
- As the object moves from infinity to the focus, how does the image move?
Case 2: A student traces the path of a ray of light passing through a rectangular glass slab
for different angles of incidence. He measures the angle of incidence ($i$), angle of refraction ($r$) and
angle of emergence ($e$) for each case.
- What is the relationship between the angle of incidence ($i$) and angle of emergence ($e$)?
- Name the perpendicular distance between the direction of the incident ray and the emergent ray.
- If the refractive index of glass is 1.5 and the speed of light in air is $3 \times 10^8$ m/s, what is
the speed of light in glass?
- A divergent lens has a focal length of 30 cm. At what distance should an object of height 5 cm from the
optical center of the lens be placed so that its image is formed 15 cm away from the lens? Find the size
Draw the ray diagram.
- The refractive index of water is 4/3 and that of glass is 3/2. Find the refractive index of glass with
respect to water. If the speed of light in glass is $2 \times 10^8$ m/s, find the speed in water.
- Two thin lenses of power +3.5 D and -2.5 D are placed in contact. Find the power and focal length of the
combination. If an object is placed 50 cm from the combination, where is the image formed?
- A convex lens of focal length 20 cm can produce a magnified virtual as well as real image. Is this
statement correct? If yes, where shall the object be placed in each case to obtain these images?
- A student holding a mirror in his hand directed the reflecting surface towards the Sun. He then directed
the light reflected on a sheet of paper held close to the mirror.
- What should he do to burn the paper?
- Which type of mirror does he have?
- Will the image of the sun be larger or smaller than the sun?
- A convex lens forms a real, inverted image of the same size as the object. Where is the object placed?
If the object is moved 5 cm towards the lens, how will the image change?
- Light rays enter from air to water. If the angle of incidence is 45 degree, will the angle of refraction
be greater or less than 45 degree? Prove using Snell's law if n=1.33.
- Why does a diamond shine more than a glass piece cut to the same shape? Explain in terms of Critical
Angle.
- If a plane mirror is rotated by an angle $\theta$, by what angle does the reflected ray rotate? Prove
it.
- Can we use a convex mirror to burn a paper by focusing sunlight? Why or why not?
- A convex lens of Refractive Index 1.5 is immersed in a liquid of Refractive Index 1.6. Will it behave as
a converging or diverging lens? Explain.
- "Objects in the mirror are closer than they appear". Why is this written on side mirrors of cars?
- Calculate the critical angle for glass-air interface if the refractive index of glass is 1.5.
