Light: Mirrors and
Lenses Class 8 Science Curiosity Chapter 10 Solutions
🟢 1. A
light ray is incident on a mirror and gets reflected by it (Fig. 10.21). The
angle made by the incident ray with the normal to the mirror is 40°. What is
the angle made by the reflected ray with the mirror?
(i) 40° (ii) 50° (iii) 45° (iv) 60°
🧠
Explanation:
📌 Given:
- Angle
of incidence (i) = 40°
👉 By law
of reflection (परावर्तन का नियम):
- Angle
of reflection (r) = 40°
📐 Angle
with mirror:
👉 = 90°
– 40° = 50°
🟢 2.
Fig. 10.22 shows three different situations where a light ray falls on a
mirror:
Draw the reflected ray in each case (Use a ruler and
protractor for accurate drawing). What is the angle of reflection in each case?
Answer:
Class 8 Science Curiosity Chapter 10 Question 3
and 4
🟢 Class
8 Science Curiosity Chapter 10 Question 3 and 4
🟢 3. In
Fig. 10.23, the cap of a sketch pen is placed in front of three types of
mirrors.
✅ Answer
(Concept Based):
🪞 Three
types of mirrors:
🔹 Plane
Mirror (समतल दर्पण)
- Image
same size 📏
- Erect
(सीधी)
- Laterally
inverted 🔄
🔹
Concave Mirror (अवतल दर्पण)
- Close
object → Image बड़ा 🔍
- Far
object → Image छोटा / inverted
🔹 Convex
Mirror (उत्तल दर्पण)
- Always
small image 🔽
- Always
erect ✔️
- Wider
view (rear-view mirror 🚗)
Answer:
4. In Fig. 10.24 the cap of a sketch pen is placed behind a
convex lens, a concave lens and a flat transparent glass piece — all at the
same distance.
Match each image with the correct type of lens or glass.
|
Image |
Lens/glass type |
|
(i) Flat transparent glass piece |
|
|
(ii) Convex lens |
|
|
(iii) Concave lens |
Answer:
🟢
Question 5 and 6 of Class 8 Science Curiosity Chapter 10
🟢 5.
When the light is incident along the normal on the mirror, which of the
following statements is true:
✅
Answer:
👉
Correct option: (ii) Angle of incidence is 0°
🧠
Explanation:
📌 Normal
(लंब) = imaginary line perpendicular to mirror
👉 When
light falls along normal:
- Angle
of incidence (i) = 0°
- Angle
of reflection (r) = 0°
🔄 Ray same
path me wapas reflect hoti hai
🟢 6.
Three mirrors — plane, concave and convex are placed in Fig. 10.25. On the
basis of the images of the graph sheet formed in the mirrors, identify the
mirrors and write their names above the mirrors.
✅
Answer:
🪞 Identification
based on image:
🔹 Plane
Mirror (समतल दर्पण)
- Image
same size 📏
- Straight lines remain straight ✔️👉 Graph sheet looks normal
🔹
Concave Mirror (अवतल दर्पण)
- Image
may be enlarged / inverted 🔍
- Lines may appear curved/distorted👉 Graph appears bigger or upside-down
🔹 Convex
Mirror (उत्तल दर्पण)
- Image
always smaller (छोटी) 🔽
- Wider field of view 👀👉 Graph looks shrunk
📌 Conclusion
Trick (Exam Tip):
- Same
size → Plane
- Bigger/Distorted
→
Concave
- Smaller
→
Convex
Class 8 Science Curiosity Chapter 10 Question 7,
8 and 9
🟢 7. In
a museum, a woman walks towards a large convex mirror (Fig. 10.26). She will
see that:
✅
Answer:
👉
Correct option: (iv) her erect image keeps increasing in size
🧠
Explanation:
🪞 Convex
Mirror (उत्तल दर्पण):
- Image
always erect (सीधी) ✔️
- Image
always diminished (छोटी)
👉 But as
object comes closer:
- Image
size increase hota hai 📈
- Still
remains smaller than object
See Answer (iii) her inverted image keeps increasing in size
and eventually it becomes erect and magnified.
🟢 8.
Hold a magnifying glass over text and identify the distance where you can see
the text bigger than they are written. Now move it away from the text. What do
you notice? Which type of lens is a magnifying glass?
✅
Answer:
🔍 Observation:
👉 Close
distance:
- Text
appears bigger (विस्तारित) 🔎
👉 Move
away:
- Image
may become blurred / inverted / smaller
🧠
Concept:
🔎 Magnifying
glass = Convex Lens (उत्तल लेंस)
- Near
object → enlarged & erect image
- Far
object → inverted image
🟢 9.
Match the entries in Column I with those in Column II.
|
Column I |
Column II |
|
(i) Concave mirror |
(a) Spherical mirror with a reflecting surface that curves
inwards. |
|
(ii) Convex mirror |
(b) It forms an image which is always erect and diminished
in size. |
|
(iii) Convex lens |
(c) Object placed behind it may appear inverted at some
distance. |
|
(iv) Concave lens |
(d) Object placed behind it always appears diminished in
size. |
✅
Answer:
|
Column I |
Column II |
|
(i) Concave mirror |
(a) ✔️ |
|
(ii) Convex mirror |
(b) ✔️ |
|
(iii) Convex lens |
(c) ✔️ |
|
(iv) Concave lens |
(d) ✔️ |
📌 Quick
Trick 🧠:
- Convex
mirror → always small
- Concave
mirror → inward curve
- Convex
lens → can invert
- Concave
lens → always small
🟢 Class
8 Science Curiosity Chapter 10 Question 10, 11 and 12
🟢 10.
Assertion: Convex mirrors are preferred for observing the traffic behind us.
Reason: Convex mirrors provide a significantly larger view
area than plane mirrors.
✅
Answer:
👉
Correct option: (i) ✔️
🧠
Explanation:
🚗 Convex
mirror:
- Wider
field of view 👀
- Covers
large area
👉 That’s
why used as rear-view mirrors
📌 Reason
correctly explains Assertion ✔️
🟢 11. In
Fig. 10.27, note that O stands for object, M for mirror, and I for image. Which
of the following statements is true?
✅
Answer:
👉
Correct option: (iii) Figure (a) indicates a concave mirror and Figure (b)
indicates a convex mirror
🧠
Explanation:
🪞 Concave
mirror:
- Can
form real/inverted image
🪞 Convex
mirror:
- Always
forms virtual, erect, smaller image
👉
Diagram observation se identify hota hai ✔️
See Answer(iv) Figure (a) indicates a plane mirror and
Figure (b) indicates a convex mirror.
12. Place a pencil behind a transparent glass tumbler (Fig.
10.28a). Now fill the tumbler halfway with water (Fig. 10.28b). How does the
pencil appear when viewed through the water? Explain why its shape appears
changed.
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