Light: Mirrors and Lenses Class 8 - Chapter 10 Curiosity

Q 1
Question
A light ray is incident on a mirror and gets reflected by it. 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°
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Q 2
Question
Fig. 10.22 shows three situations where a light ray falls on a mirror: (i) along the normal; (ii) the mirror is tilted but the ray still falls along the normal to the tilted surface; (iii) the mirror is tilted and the ray falls at 20° from the normal. Draw the reflected ray in each case. What is the angle of reflection in each case?
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Q 3
Question
In Fig. 10.23, the cap of a sketch pen is placed in front of three types of mirrors. Match each image with the correct mirror: (i) Plane mirror, (ii) Convex mirror, (iii) Concave mirror.
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Q 4
Question
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: (i) Flat transparent glass piece, (ii) Convex lens, (iii) Concave lens.
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Q 5
Question
When the light is incident along the normal on the mirror, which of the following statements is true?
(i) Angle of incidence is 90°
(ii) Angle of incidence is 0°
(iii) Angle of reflection is 90°
(iv) No reflection of light takes place in this case
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Q 6
Question
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.
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Q 7
Question
In a museum, a woman walks towards a large concave mirror. She will see that:
(i) her erect image keeps decreasing in size.
(ii) her inverted image keeps decreasing in size.
(iii) her inverted image keeps increasing in size and eventually becomes erect and magnified.
(iv) her erect image keeps increasing in size.
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Q 8
Question
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?
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Q 9
Question
Match the entries in Column I with those in Column II.
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Q 10
Question
Assertion: Convex mirrors are preferred for observing the traffic behind us. Reason: Convex mirrors provide a significantly larger view area than plane mirrors. Choose the correct option:
(i) Both correct, Reason is the correct explanation.
(ii) Both correct, but Reason is not the correct explanation.
(iii) Assertion correct, Reason incorrect.
(iv) Both incorrect.
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Q 11
Question
In Fig. 10.27, O stands for object, M for mirror, and I for image. Which of the following statements is true?
(i) Figure (a) plane mirror and (b) concave mirror.
(ii) Figure (a) convex mirror and (b) concave mirror.
(iii) Figure (a) concave mirror and (b) convex mirror.
(iv) Figure (a) plane mirror and (b) convex mirror.
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Q 12
Question
Place a pencil behind a transparent glass tumbler. Now fill the tumbler halfway with water. How does the pencil appear when viewed through the water? Explain why its shape appears changed.
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Project 1
Project
Visit a nearby hospital or the clinic of an ENT specialist, or a dentist, with your teacher or parents. Request the doctor to show you the mirrors used for examining ear, nose, throat, and teeth. Identify the kind of mirror used in these instruments.
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Key Points
These instruments mostly use concave mirrors.
Key Points / Good Practices
Visit only with a teacher or parent.
Politely ask the doctor to show the examining mirrors.
Dental and ENT mirrors are usually concave.
A concave mirror gives an enlarged view when held close.
Note where the mirror is small enough to fit inside the mouth.
Write down which mirror is used for each instrument.
Dental and ENT examining mirrors are concave because they give a magnified close-up view.

Project 2
Project
Harnessing sunlight is key to solving future energy challenges. In devices like solar cookers, mirrors are used to converge sunlight and generate heat. Think of a design for a solar cooker for your school or home and prepare a detailed proposal for it including the budget required.
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Key Points
Use a concave reflector to focus sunlight onto the pot.
Key Points / Good Practices
Use a curved (concave) reflecting surface to converge sunlight.
Place the cooking pot at the focus point where light gathers.
Use an insulated box to trap the heat.
List materials: reflector, box, glass cover, black pot.
Estimate the cost of each material for the budget.
Explain how it saves electricity and fuel.
A good proposal uses a concave reflector to focus sunlight onto a pot, with a clear materials budget.

Project 3
Project
Use online tools or animation to do virtual experiments with spherical mirrors and lenses. Move objects in the simulation and observe how the image changes.
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Key Points
Simulations let you safely test many positions.
Key Points / Good Practices
Choose a trusted optics simulation tool.
Start with a concave mirror and move the object slowly.
Note when the image flips from erect to inverted.
Repeat with a convex mirror and both lenses.
Record how size and orientation change with distance.
Compare your results with what the chapter predicts.
Virtual experiments let you watch how images change as objects move near or far.