Light – Reflection and Refraction Science - Light – Reflection and Refraction

The laws of reflection hold good for:

A 10mm long awl pin is placed vertically in front of a concave mirror. A 5mm long image of the awl pin is formed at 30cm in front of the mirror. The focal length of this mirror is:

Figure shows a ray of light as it travels from medium A to medium B. Refractive index of the medium B relative to medium A is:

Which of the following ray diagrams is correct for the ray of light incident on a lens shown in Fig.?

Beams of light are incident through the holes A and B and emerge out of box through the holes C and D respectively as shown in the Figure. Which of the following could be inside the box?

Draw ray diagrams showing the image formation by a convex lens when an object is placed:Between focus and twice the focal length of the lens.

Draw ray diagrams showing the image formation by a concave mirror when an object is placed:
At centre of curvature of the mirror.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.Object is placed between infinity and device, image formed is diminished and between pole and focus, behind it.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.
Object is placed between device and its focus, image formed is enlarged and behind it.

Draw ray diagrams showing the image formation by a convex lens when an object is placed: Between optical centre and focus of the lens.

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80cm and the lens?

A convex lens of focal length 20cm can produce a magnified virtual as well as real image. Is this a correct statement? If yes, where shall the object be placed in each case for obtaining these images?

Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever may be angle of incidence. Show the same with the help of diagram.

Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

Why does a light ray incident on a rectangular glass slab immersed in any medium emerges parallel to itself? Explain using a diagram.

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under,
Position of candle = 12.0cm
Position of convex lens = 50.0cm
Position of the screen = 88.0cm

1. What is the focal length of the convex lens?
2. Where will the image be formed if he shifts the candle towards the lens at a position of 31.0cm?
3. What will be the nature of the image formed if he further shifts the candle towards the lens?
4. Draw a ray diagram to show the formation of the image in case (iii) as said above.

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

You are given water, mustard oil, glycerine and kerosene. In which of these media a ray of light incident obliquely at same angle would bend the most?

1. Kerosene.
2. Water.
3. Mustard oil.
4. Glycerine.

Which of the following statements is true?

1. A convex lens has 4 dioptre power having a focal length 0.25m.
2. A convex lens has -4 dioptre power having a focal length 0.25m.
3. A concave lens has 4 dioptre power having a focal length 0.25m.
4. A concave lens has -4 dioptre power having a focal length 0.25m.

Which of the following can make a parallel beam of light when light from a point source is incident on it?

1. Concave mirror as well as convex lens.
2. Convex mirror as well as concave lens.
3. Two plane mirrors placed at 90° to each other.
4. Concave mirror as well as concave lens.

Under which of the following conditions a concave mirror can form an image larger than the actual object?

1. When the object is kept at a distance equal to its radius of curvature.
2. When object is kept at a distance less than its focal length.
3. When object is placed between the focus and centre of curvature.
4. When object is kept at a distance greater than its radius of curvature.

The laws of reflection hold good for:

1. Plane mirror only.
2. Concave mirror only.
3. Convex mirror only.
4. All mirrors irrespective of their shape.

Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5. Find out the absolute refractive index of diamond.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.

Object is placed between the focus and device, image formed is enlarged and on the same side as that of the object.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.

Object is placed between infinity and device, image formed is diminished and between pole and focus, behind it.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.

Object is placed between infinity and device, image formed is diminished and between focus and optical centre on the same side as that of the object.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.
Object is placed between device and its focus, image formed is enlarged and behind it.

Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever may be angle of incidence. Show the same with the help of diagram.

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80cm and the lens?

Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

How is the refractive index of a medium related to the speed of light? Obtain an expression for refractive index of a medium with respect to another in terms of speed of light in these two media?

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

Why does a light ray incident on a rectangular glass slab immersed in any medium emerges parallel to itself? Explain using a diagram.

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under,
Position of candle = 12.0cm
Position of convex lens = 50.0cm
Position of the screen = 88.0cm

1. What is the focal length of the convex lens?
2. Where will the image be formed if he shifts the candle towards the lens at a position of 31.0cm?
3. What will be the nature of the image formed if he further shifts the candle towards the lens?
4. Draw a ray diagram to show the formation of the image in case (iii) as said above.