Chapter 1 Physical Environment VSAQs
Question 1. What is the critical angle of a diamond with respect to air?
Answer:
The critical angle of a diamond with respect to air Is 24.5°
Question 2. What kind of image is formed in a plane mirror?
Answer:
Virtual image is formed in a plane mirror.
Question 3. Which kind of image can be cast on a screen?
Answer:
Real image can be cast on a screen.
WBBSE Class 8 Light very short answer questions
Question 4. If the angle between two plane mirrors is 60° and if an object is placed in between them, how many images will be formed?
Answer:
The number of images that will be formed is 360°
1= 5. So five virtual images will be
Question 5. If two plane mirrors are placed parallel facing each other, and if an object is placed in between them then how many Answer: images will be formed?
Answer:
If the two plane mirrors are placed parallel facing each other, then an infinite number of images will be formed. But except for a finite number of images, most of the images cannot be seen as they would become faint.
Read And Learn More WBBSE Solutions For Class 8 School Science Very Short Answer Type Questions
Question 6. In which medium the velocity of light is maximum?
Answer:
The velocity of light is maximum in a vacuum.
Question 7. On which factors does the refractive index of a medium with respect to another depend?
Answer:
Refractive index depends on the nature of the two media and on the color of a ray of light.
Question 8. Give one example of total internal reflection which is observed in nature.
Answer:
Mirage, formed during daytime in the desert is an example of total internal reflection observed in nature.
Question 9. If a ray of light is incident on a plane mirror making an angle of 60° with the plane of the mirror, what will be the value of the angle of reflection?
Answer:
If the angle between the plane mirror and the incident ray is 60°, then the angle of incidence is (90° – 60°) = 30°.
Since, from the laws of reflection, we know that the angle of incidence is the same as the angle of reflection, so the angle of reflection, in this case, will be 30°.
If a ray of light is incident on a plane mirror making an angle of 90° with the plane of the mirror, what will be the value of the angle of reflection?
Question 10. If the ray of light is incident on a plane mirror making an angle of 90° with the plane of the mirror, then the angle of incidence is (90? – 90?)
Answer:
=0°. Since, from the laws of reflection, we know that the angle of incidence is the same as the angle of reflection, the angle of reflection will be 0°.
Very short answer questions on light for Class 8
Question 11. If the distance between an object and a plane mirror is 10 cm, what will be the distance between the object and its virtual image?
Answer:
If the distance between an object and a plane mirror is 10 cm, then the distance between the plane mirror and the virtual image of the object is 10 cm. So the total distance between the object and its virtual image is (10 + 10) cm = 20 cm.
Question 12. An object is placed in front of a plane mirror. If the object is moved 2 cm away from the mirror, how much does the virtual image move from the object?
Answer:
If the object is moved 2 cm away from the mirror, then the distance between the object and the plane mirror is (x + 2) gm.
So the distance between the object and its virtual image will be 2(x + 2) cm.
So the distance by which the virtual image will move away from the object is = 2(x+2) – 2x = 4cm.
Question 13. The critical angle of glass with respect to air
Answer:
The critical angle of glass with respect to air
Is 42°. If a ray of light, when passing from glass to air is incident at the glass-air interface with the angle of incidence of 42°, what will be the angle of refraction in the air?
If the critical angle of glass with respect to air is 42? then for a light passing from glass to air, the angle of refraction will be 90? in air.
Question 14. Where do we observe superior mirage?
Answer:
Superior mirage is observed in colder countries during winter.
Question 15. When viewed from the top, the depth of water in a water-filled bucket seems to be raised. Which property of light is responsible for this phenomenon?
Answer:
Refraction of light is responsible for this phenomenon.
Question 16. An image of a tree is formed on the surface of the water of a pond. Is it an erect or an inverted image?
Answer:
Inverted real image.
WBBSE Chapter 1 light quick answer solutions
Question 17. Which principle of light is utilized in making periscope?
Answer:
A periscope works on the reflection of light from two plane mirrors arranged parallel to one another.
Question 18. Two plane mirrors are inclined at an angle of 72° to each other with an object placed between them. How many images of the object are formed by successive reflections?
Answer:
360° Number of images = 360°/72°- 5.
Question 19. Find out the odd term :
Answer:
Total internal reflection, critical angle, refraction, reflection.
Refraction.
Light concepts summary with very short answers for Class 8
Question 20. What do you mean by the statement that the critical angle of glass is 42° ?
Answer:
Critical angle of glass is 42°, this means that when a ray of light of any given colour tends to travel from glass to air, then for an angle of incidence of 42° in glass, the angle of refraction in the air is 90°.
Question 21. Sitting in front of a plane mirror when we write with our right hand, it appears in the mirror that we are writing with our left hand. Which phenomenon is responsible for this?
Answer:
Lateral inversion of image.