DAV Public School Class 8 chapter 16 question answer and extra question science
Answers
Answer:
Explanation:
Question 1.
Define light.
Answer:
Light is defined as a form of energy that stimulates sight and makes things visible.
Question 2.
What is reflection?
Answer:
The bouncing back of light into the same medium after it falls on a surface is called reflection.
Question 3.
What is a mirror?
Answer:
A piece of glass with a shiny metal-covered at back, that reflects light, producing an image of the object in front of it is known as mirror.
Question 4.
State the two laws of reflection.
Answer:
The two laws of reflection are:
The angle of incidence is always equal to the angle of reflection.
The incident ray, the reflected ray and normal all lie in the same plane.
Question 5.
How do we see various objects?
Answer:
We see various objects due to reflection. As we know all surface reflect light, when light falls on any object, it reflects the light. The reflected light reaches our eyes and we are able to see the object.
Question 6.
What do you mean by reflected ray?
Answer:
The ray of light which is returned back into the same medium after the incident ray strikes the surface ’ is called reflected ray.
Question 7.
What is irregular reflection?
Answer:
Irregular reflection is defined as the reflection of light from an uneven surface. In irregular reflection, the reflected beam is not parallel.
Question 8.
List the characteristics of an image formed in a plane mirror.
Answer:
he characteristics of an image formed in a plane mirror are:
It is virtual.
It is erect.
It is of same size as the object.
Question 9.
What is lateral inversion?
Answer:
The phenomenon of changing left side to right and right side to left by the mirror while forming image is called lateral inversion.
Question 10.
What is the far point and near point of the human eye with normal vision?
Answer:
In optics, the farthest and closest point at which an object can be brought into focus by the eye are called far point and near point of the eye respectively. The far point of the human eye with normal vision is infinity. The near point of the human eye with normal vision is 25 cm.
Question 11.
What is aqueous humour?
Answer:
The space between the cornea and lens is filled with a liquid called the aqueous humour.
Question 12.
Differentiate between rod and cone cells.
Answer:
Rods are the rod-shaped cells present in the retina of an eye which are sensitive to dim light whereas cones are the cone-shaped cells present in the retina of the eye which are sensitive to bright light.
Question and Answers for class 8 science
1. Define light.
Light is defined as a form of energy that stimulates sight and makes things visible.
2. What is a mirror?
A piece of glass with a shiny metal-covered back, that reflects light, producing an image of the object in front of it is known as a mirror.
3. State the two laws of reflection.
- The angle of incidence is always equal to the angle of reflection.
- The incident ray, the reflected ray and normal all lie in the same plane
4. What is lateral inversion?
The phenomenon of changing left side to right and right side to left by the mirror while forming an image is called lateral inversion.
5. What is aqueous humour?
The space between the cornea and lens is filled with a liquid called the aqueous humour.