What is critical angle?

What is the refraction of light?

Differentiate: reflection of light and total internal reflection of light.

Differentiate: concave lens and convex lens

Differentiate: near point of the eye and far point of the eye

Differentiate: shortsightedness and longsightedness

Differentiate: color blindness and night blindness

Between glass and water, glass is considered a denser medium and water is a rarer medium. Why?

When a coin is placed in a glass containing water, it appears to rise a bit. Give reason.

When the letters written on the paper are observed from the top of a glass slab, the letters appear to be slightly raised, why?

Stars twinkle. Give reason.

The sun appears on the horizon about two minutes before the actual sunrise.

A diamond appears to shine but a piece of glass cut to the same shape does not shine.

Sunlight is refracted when it is passed through a prism. Give reason.

A convex lens converges light rays. Why?

A concave lens diverges the rays of light. Why?

The deficiency of vitamin A in the body is one of the main causes of night blindness. Justify.

Color blindness occurs when the cone cells of the retina stop functioning. Give reason.

Write the laws of refraction of light.

When a light ray passes from water to air, the angle of incidence and angle of refraction formed at the water-air separation layer are 40.5^o and 60^o respectively. Draw a ray diagram showing the refraction and write the reason why an object outside appears to be farther away from its actual position when it is viewed by an observer inside the water.

What is a total internal reflection of light?

Write two conditions necessary for total internal reflection of light.
 

At present, data can be transmitted at a very fast rate through fiber internet. Mention the role of total internal reflection of light in fiber internet.

In endoscopy, colonoscopy, and keyhole surgery, how is total internal reflection of light applicable to the devices used to send light to the internal organs of the human body without incisions?

What is a dispersion of light?

Mention the reason for the dispersion of light.

The magnification is less than 1. What does it mean?

A student is given a convex lens of focal length 25 cm. He places a burning candle at a distance of 40 cm away from the lens. At what distance will he obtain a sharp image of the candle?

How is it possible for doctors to examine internal body parts seeing the image of the inside of the body clearly?

Draw a ray diagram showing the refraction of light through a glass slab.

Draw a ray diagram showing the dispersion of light through a prism.

A person is curious to know why a rainbow always appears semicircular and of the same size. Write down the solution to his curiosity. Include in your answer the position of the sun in the rainbow, the position of the water droplets in the air, and the process of dispersion of light.

Define center of curvature of a lens.

Define the optical center of a lens.

Define the principle axis of a lens.

Define the focus of a lens.

Define the power of a lens.

The powers of the two convex lenses are +2D and +4D respectively.

1. Which of them is thicker? Give reason.
2. Calculate the focal length of each lens.

In which case is the image formed by a convex lens real and of the same size as the object? Show the ray diagram.

How can the light dispersed by a prism be converted back into white light?

The focal lengths of the two lenses are 20cm and -20cm respectively. Mention the types of these two lenses. Out of these two lenses, which one forms a virtual and magnified image when an object is kept 16cm away from the lens? Explain it by drawing a scaled ray diagram.

Write the function of the ciliary muscle in the human eye.

Write the function of the cornea in the human eye.

Write the function of the lens in the human eye.

Write the function of the iris in the human eye.

Write the function of the pupil in the human eye.

Write the function of the retina in the human eye.

Write any two problems that may be seen in corneal injury.

Explain the role of the ciliary muscle in the change in the thickness of the eye lens when a student sitting in a classroom shifts his eyes from the letter written on the whiteboard to a distant object seen out of the window.

A student is the class has difficulties in seeing the letters written on the whiteboard when he sits on the last bench but he sees them clearly when he sits on the first bench. Based on this, answer the following questions:

1. What type of defect of vision does the student have?
2. Draw a ray diagram showing this type of defect of vision of the student.
3. Write any two reasons for this defect.
4. Explain, with a ray diagram, the role of the lens used to correct this defect.

Explain, with a ray diagram, the role of the lens used to correct long-sightedness.

A student concludes that ‘The effect of defect of vision is more on a person wearing spectacles with thick lenses than one wearing that with thin lenses.’ Is this understanding correct? Justify with appropriate reasons.

Compare the use of spectacles and the use of contact lenses to correct visual defects.

Explain the laser surgery method used to solve eyesight problems.

What is a cataract? Write the role of the intraocular lens developed by Nepal's opthalmologist Dr. Sanduk Ruit in the treatment of cataracts.

If the speed of light in air and glass are $\rm 3 \times 10^{8}$ m/s and $\rm 2 \times 10^{8}$ m/s respectively, then calculate the refractive index of glass with respect to air.

The refractive index of a diamond is 2.42. If the speed of light in air is $\rm 3 \times 10^{8}$ m/s, calculate the speed of light in a diamond.

When a ray of light falls on the surface of a plastic block, the angle made by the ray with the normal and the angle of refraction is found to be 45^o and 33^o respectively. Calculate the refractive index of the plastic.

Calculate the power of a lens having a focal length of 25 cm.

The power of the lens used in the spectacles worn by a student is -6 D. Calculate the focal length of the lens. Also, mention the type of lens.

In which medium shown in the diagram, critical angle is formed before total internal reflection? 

A person is using a spectacle having lens of power -2.5 D. What could be the problem in the eye of the man?

If power of the lens used in spectacle is -3D, what is its focal length?

A ray diagram showing refraction of light is given alongside. Complete it to show total internal reflection.

Defect of vision of two students A and B are shown in the diagram.

1. Between them, who can read the letters written in the board from the last bench?
2. Write any two differences between eyes A and B on the basis of cause of defects.
3. Sketch a ray diagram to correct the defect of eye B.

What type of lens is used for the correction of defects of vision shown in the diagram?

A ray of light is passed inside the prism.

1. Find the value of $\rm \theta _1$.
2. What will be the direction of ray after Q?

A type of defect of vision is shown in the diagram. Write any two causes of this defect. How can the defect be remedied? Show with diagram.

What is the imaginary line joining two centres of curvature of a lens called?

A student has faced difficulty to read letters of book at a normal distance due to defects of vision. How is the defect removed by the use of spectacles? Show it with ray diagram only.

A lens can form real and magnified image of the object kept in between F and 2F of it. Mention the type of defect of vision which can be removed by using such lenses.

Some properties of light are shown in the diagram of semicircular glass slab given alongside. Complete the following table on the basis of it. What is the difference between the refraction of light in a rectangular and semicircular glass slabs?

If ray is passing in new medium by making more angle after refraction, what type of optical medium is it?

Complete the ray diagram showing the image formed by the prism.

Image formed by three different lenses A, B and C and their natures are given in the table below.

1. Which of two lenses among them can be used in the remedy of long sightedness?
2. Draw a ray diagram for the image formed assuming 3 cm focal length of lens B.
3. Write the nature of image formed by the lens C when object is kept at 2F of it.

What is critical angle?

What is the refraction of light?

Differentiate: reflection of light and total internal reflection of light.

Differentiate: concave lens and convex lens

Differentiate: near point of the eye and far point of the eye

Differentiate: shortsightedness and longsightedness

Differentiate: color blindness and night blindness

Between glass and water, glass is considered a denser medium and water is a rarer medium. Why?

When a coin is placed in a glass containing water, it appears to rise a bit. Give reason.

When the letters written on the paper are observed from the top of a glass slab, the letters appear to be slightly raised, why?

Stars twinkle. Give reason.

The sun appears on the horizon about two minutes before the actual sunrise.

A diamond appears to shine but a piece of glass cut to the same shape does not shine.

Sunlight is refracted when it is passed through a prism. Give reason.

A convex lens converges light rays. Why?

A concave lens diverges the rays of light. Why?

The deficiency of vitamin A in the body is one of the main causes of night blindness. Justify.

Color blindness occurs when the cone cells of the retina stop functioning. Give reason.

Write the laws of refraction of light.

When a light ray passes from water to air, the angle of incidence and angle of refraction formed at the water-air separation layer are 40.5^o and 60^o respectively. Draw a ray diagram showing the refraction and write the reason why an object outside appears to be farther away from its actual position when it is viewed by an observer inside the water.

What is a total internal reflection of light?

Write two conditions necessary for total internal reflection of light.
 

At present, data can be transmitted at a very fast rate through fiber internet. Mention the role of total internal reflection of light in fiber internet.

In endoscopy, colonoscopy, and keyhole surgery, how is total internal reflection of light applicable to the devices used to send light to the internal organs of the human body without incisions?

What is a dispersion of light?

Mention the reason for the dispersion of light.

The magnification is less than 1. What does it mean?

A student is given a convex lens of focal length 25 cm. He places a burning candle at a distance of 40 cm away from the lens. At what distance will he obtain a sharp image of the candle?

How is it possible for doctors to examine internal body parts seeing the image of the inside of the body clearly?

Draw a ray diagram showing the refraction of light through a glass slab.

Draw a ray diagram showing the dispersion of light through a prism.

A person is curious to know why a rainbow always appears semicircular and of the same size. Write down the solution to his curiosity. Include in your answer the position of the sun in the rainbow, the position of the water droplets in the air, and the process of dispersion of light.

Define center of curvature of a lens.

Define the optical center of a lens.

Define the principle axis of a lens.

Define the focus of a lens.

Define the power of a lens.

The powers of the two convex lenses are +2D and +4D respectively.

1. Which of them is thicker? Give reason.
2. Calculate the focal length of each lens.

In which case is the image formed by a convex lens real and of the same size as the object? Show the ray diagram.

How can the light dispersed by a prism be converted back into white light?

The focal lengths of the two lenses are 20cm and -20cm respectively. Mention the types of these two lenses. Out of these two lenses, which one forms a virtual and magnified image when an object is kept 16cm away from the lens? Explain it by drawing a scaled ray diagram.

Write the function of the ciliary muscle in the human eye.

Write the function of the cornea in the human eye.

Write the function of the lens in the human eye.

Write the function of the iris in the human eye.

Write the function of the pupil in the human eye.

Write the function of the retina in the human eye.

Write any two problems that may be seen in corneal injury.

Explain the role of the ciliary muscle in the change in the thickness of the eye lens when a student sitting in a classroom shifts his eyes from the letter written on the whiteboard to a distant object seen out of the window.

A student is the class has difficulties in seeing the letters written on the whiteboard when he sits on the last bench but he sees them clearly when he sits on the first bench. Based on this, answer the following questions:

1. What type of defect of vision does the student have?
2. Draw a ray diagram showing this type of defect of vision of the student.
3. Write any two reasons for this defect.
4. Explain, with a ray diagram, the role of the lens used to correct this defect.

Explain, with a ray diagram, the role of the lens used to correct long-sightedness.

A student concludes that ‘The effect of defect of vision is more on a person wearing spectacles with thick lenses than one wearing that with thin lenses.’ Is this understanding correct? Justify with appropriate reasons.

Compare the use of spectacles and the use of contact lenses to correct visual defects.

Explain the laser surgery method used to solve eyesight problems.

What is a cataract? Write the role of the intraocular lens developed by Nepal's opthalmologist Dr. Sanduk Ruit in the treatment of cataracts.

If the speed of light in air and glass are $\rm 3 \times 10^{8}$ m/s and $\rm 2 \times 10^{8}$ m/s respectively, then calculate the refractive index of glass with respect to air.

The refractive index of a diamond is 2.42. If the speed of light in air is $\rm 3 \times 10^{8}$ m/s, calculate the speed of light in a diamond.

When a ray of light falls on the surface of a plastic block, the angle made by the ray with the normal and the angle of refraction is found to be 45^o and 33^o respectively. Calculate the refractive index of the plastic.

Calculate the power of a lens having a focal length of 25 cm.

The power of the lens used in the spectacles worn by a student is -6 D. Calculate the focal length of the lens. Also, mention the type of lens.

In which medium shown in the diagram, critical angle is formed before total internal reflection? 

A person is using a spectacle having lens of power -2.5 D. What could be the problem in the eye of the man?

If power of the lens used in spectacle is -3D, what is its focal length?

A ray diagram showing refraction of light is given alongside. Complete it to show total internal reflection.

Defect of vision of two students A and B are shown in the diagram.

1. Between them, who can read the letters written in the board from the last bench?
2. Write any two differences between eyes A and B on the basis of cause of defects.
3. Sketch a ray diagram to correct the defect of eye B.

What type of lens is used for the correction of defects of vision shown in the diagram?

A ray of light is passed inside the prism.

1. Find the value of $\rm \theta _1$.
2. What will be the direction of ray after Q?

A type of defect of vision is shown in the diagram. Write any two causes of this defect. How can the defect be remedied? Show with diagram.

What is the imaginary line joining two centres of curvature of a lens called?

A student has faced difficulty to read letters of book at a normal distance due to defects of vision. How is the defect removed by the use of spectacles? Show it with ray diagram only.

A lens can form real and magnified image of the object kept in between F and 2F of it. Mention the type of defect of vision which can be removed by using such lenses.

Some properties of light are shown in the diagram of semicircular glass slab given alongside. Complete the following table on the basis of it. What is the difference between the refraction of light in a rectangular and semicircular glass slabs?

If ray is passing in new medium by making more angle after refraction, what type of optical medium is it?

Complete the ray diagram showing the image formed by the prism.

Image formed by three different lenses A, B and C and their natures are given in the table below.

1. Which of two lenses among them can be used in the remedy of long sightedness?
2. Draw a ray diagram for the image formed assuming 3 cm focal length of lens B.
3. Write the nature of image formed by the lens C when object is kept at 2F of it.