Reflection of Light Exe-7A Numericals Concise Physics ICSE Class-9 Selina Publishers. There is the solutions of Numerical Questions of your latest textbook which is applicable in 2024-25 academic session. Visit official Website CISCE for detail information about ICSE Board Class-9.
Reflection of Light Exe-7A Numericals
Concise Physics ICSE Class-9 Selina Publishers
| Board | ICSE |
| Class | 9 |
| Subject | Physics |
| Writer / Publication | Concise Selina Publishers |
| Chapter-7 | Reflection of Light |
| Exe-7A | Laws of Reflection |
| Topics | Solution of Numerical |
| Academic Session | 2024-2025 |
Exercise- 7A Laws of Reflection
page -170
Numericals :
Que: 1- A ray is incident on a plane mirror . Its reflected ray is perpendicular to the incident ray . Find the angle of incidence .
Solution- Angle of incidence (i) + Angle of reflection(r) = 90o But, as per the laws of reflection, i = r
Therefore, 2 i = 90o
Or, i = r = 45o
Que: 2- A man standing in front of a plane mirror finds his image at a distance 6 metre from himself. What is the distance of man from the mirror?
Solution- Distance between man and his image = 6mDistance between man and mirror + distance between mirror and image = 6m
But, Distance between man and mirror (object distance) = distance between mirror and image (image distance)
Therefore, distance of man from mirror = 6/2 =3m.
Que:3 –An insect is sitting in front of a plane mirror at a distance 1 m from it.
(a) Where is the image of the insect formed?
(b) What is the distance between the insect and its image?
Solution- (a) Image of the insect is formed 1m behind the mirror.
(b) Distance between the insect and the man = 2m.
Que: 4- An object is kept at 60 cm in front of a plane mirror. If the mirror is now moved 25 cm away from the object, how does the image shift from its previous position?
Solution- Initially, distance of the object from the mirror = 60 cm. Therefore, image is formed at a distance 60 cm from the mirror, behind it.
Thus, initial distance between the object and image = 60 + 60 = 120 cm
If the mirror is moved 25 cm away from the object,
The new distance of the object from the mirror = 60 + 25 = 85 cm
The new image is now at a distance 85 cm from the mirror behind it.
Thus, new distance of the image from the object = 85 + 85 = 170 cm
Taking the position of the object as reference point, the distance between the two positions of the image = new distance of image from the object – initial distance of the image from the object
= (170 – 120) cm = 50 cm
Thus, the image shifts 50cm away.
Que: 5- An optician while testing the eyes of a patient keeps a chart of letters 3 m behind the patient and asks him to see the letters on the image of chart formed in a plane mirror kept at distance 2 m in front of him. At what distance is the chart seen by the patient?
Solution- Distance between man and chart = 3m
Distance between man and mirror = 2m
Therefore, distance between chart and mirror = 5 m
Now, final image is formed on the mirror, which is at a distance of 2 m from the man, therefore, the chart as seen by patient is (5m + 2m =) 7m away.
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