It is necessary that we take proper care of our eyes. If there is any problem we should go to an eye specialist. Have a regular check-up. • If advised, we should use suitable spectacles. • Too little or too much light is bad for eyes. Insufficient light causes eyestrain and headaches. Too much lightRead more
It is necessary that we take proper care of our eyes. If there is any problem we should go to an eye specialist. Have a regular check-up.
• If advised, we should use suitable spectacles.
• Too little or too much light is bad for eyes. Insufficient light causes eyestrain and headaches. Too much light, like that of the sun, a powerful lamp or a laser torch can injure the retina.
• We should not look at the sun or a powerful light directly.
• Never rub our eyes. If particles of dust go into our eyes, wash our eyes with clean water. If there is no improvement go to a doctor.
• Wash our eyes frequently with clean water.
• Always read at the normal distance for vision. Do not read by bringing your book too close to our eyes or keeping it too far.
If you touch your left ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with left hand. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
If you touch your left ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with left hand.
Fix a white sheet of stiff paper on a drawing board or a table. Take a comb and close all its openings except one in the middle. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side. With slight adjustment of the torch and the combRead more
Fix a white sheet of stiff paper on a drawing board or a table. Take a comb and close all its openings except one in the middle. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side. With slight adjustment of the torch and the comb we will see a ray of light along the paper on the other side of the comb. Keep the comb and the torch steady. Place a strip of plane mirror in the path of the light ray. Let the sheet project a little beyond the edge of the Table. Cut the projecting portion of the sheet in the middle. Look at the reflected ray. Make sure that the reflectedray extends to the projected portion of the paper. Bend that part of the projected portion on which the reflected ray falls. Bring the paper back to the original position.
When the whole sheet of paper is spread on the table, it represents one plane. The incident ray, the normal at the point of incidence and the reflected ray are all in this plane. When we bend the paper you create a plane different from the plane in which the incident ray and the normal lie. Then we do not see the reflected ray. It indicates that the incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.
Laws of reflection: • The angle of incidence is always equal to the angle of reflection. • The incident ray, the reflected ray and the normal to the surface at the point of incidence lie in the same plane. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
Laws of reflection:
• The angle of incidence is always equal to the angle of reflection.
• The incident ray, the reflected ray and the normal to the surface at the point of incidence lie in the same plane.
(a) A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place. (b) Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place. (c) A cardboard has irregular surfacRead more
(a) A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(b) Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(c) A cardboard has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(d) A marble floor with water spread over it provides a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(e) A mirror has a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(f) A piece of paper may appear smooth but it has many minor irregularities. So, when a beam of light reflects from it, a diffused reflection will take place.
Which is the best website providing NCERT Solutions?
Tiwari Academy https://www.tiwariacademy.com/
Tiwari Academy
https://www.tiwariacademy.com/
See lessExplain how you can take care of your eyes.
It is necessary that we take proper care of our eyes. If there is any problem we should go to an eye specialist. Have a regular check-up. • If advised, we should use suitable spectacles. • Too little or too much light is bad for eyes. Insufficient light causes eyestrain and headaches. Too much lightRead more
It is necessary that we take proper care of our eyes. If there is any problem we should go to an eye specialist. Have a regular check-up.
• If advised, we should use suitable spectacles.
• Too little or too much light is bad for eyes. Insufficient light causes eyestrain and headaches. Too much light, like that of the sun, a powerful lamp or a laser torch can injure the retina.
• We should not look at the sun or a powerful light directly.
• Never rub our eyes. If particles of dust go into our eyes, wash our eyes with clean water. If there is no improvement go to a doctor.
• Wash our eyes frequently with clean water.
• Always read at the normal distance for vision. Do not read by bringing your book too close to our eyes or keeping it too far.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessChoose the correct option: Image formed by a plane mirror is
(b) virtual, behind the mirror and of the same size as the object https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
(b) virtual, behind the mirror and of the same size as the object
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessChoose the correct option: Angle of incidence is equal to the angle of reflection
(a) Always https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
(a) Always
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessFill in the blanks: Night birds have ____________ cones than rods in their eyes.
Night birds have less cones than rods in their eyes. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
Night birds have less cones than rods in their eyes.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessFill in the blanks: The size of the pupil becomes ____________ when you see in dim light.
The size of the pupil becomes large when you see in dim light. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
The size of the pupil becomes large when you see in dim light.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessFill in the blanks: If you touch your ____________ ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with ____________.
If you touch your left ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with left hand. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
If you touch your left ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with left hand.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessDescribe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
Fix a white sheet of stiff paper on a drawing board or a table. Take a comb and close all its openings except one in the middle. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side. With slight adjustment of the torch and the combRead more
Fix a white sheet of stiff paper on a drawing board or a table. Take a comb and close all its openings except one in the middle. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side. With slight adjustment of the torch and the comb we will see a ray of light along the paper on the other side of the comb. Keep the comb and the torch steady. Place a strip of plane mirror in the path of the light ray. Let the sheet project a little beyond the edge of the Table. Cut the projecting portion of the sheet in the middle. Look at the reflected ray. Make sure that the reflectedray extends to the projected portion of the paper. Bend that part of the projected portion on which the reflected ray falls. Bring the paper back to the original position.
When the whole sheet of paper is spread on the table, it represents one plane. The incident ray, the normal at the point of incidence and the reflected ray are all in this plane. When we bend the paper you create a plane different from the plane in which the incident ray and the normal lie. Then we do not see the reflected ray. It indicates that the incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessState the laws of reflection.
Laws of reflection: • The angle of incidence is always equal to the angle of reflection. • The incident ray, the reflected ray and the normal to the surface at the point of incidence lie in the same plane. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
Laws of reflection:
• The angle of incidence is always equal to the angle of reflection.
• The incident ray, the reflected ray and the normal to the surface at the point of incidence lie in the same plane.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See lessMention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case. (a) Polished wooden table (b) Chalk powder (c) Cardboard surface (d) Marble floor with water spread over it (e) Mirror (f) Piece of paper
(a) A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place. (b) Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place. (c) A cardboard has irregular surfacRead more
(a) A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(b) Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(c) A cardboard has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(d) A marble floor with water spread over it provides a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(e) A mirror has a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(f) A piece of paper may appear smooth but it has many minor irregularities. So, when a beam of light reflects from it, a diffused reflection will take place.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-16/
See less