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A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm?
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A real image formed by a concave mirror is 4.5 times the size of the o...
Answer:
Given,
Magnification (m) = 4.5
Object distance (u) = -20 cm (negative sign indicates that the object is placed in front of the mirror)
Let the focal length of the mirror be (f) cm.
Using the mirror formula,
1/f = 1/u + 1/v
where v is the image distance.
Magnification (m) = -v/u
Substituting the given values,
4.5 = -v/-20
v = 90 cm
Now, using the magnification formula,
m = -v/u = h'/h = 4.5
where h' is the height of the image and h is the height of the object.
h'/h = -v/u = 4.5
h'/h = -90/-20 = 4.5
h'/h = 9/2
Let the height of the object be (h) cm.
The height of the image (h') will be 4.5 times the height of the object.
h' = 4.5h = (9/2)h
Substituting the given value of object distance (u),
1/f = 1/-20 + 1/90
1/f = -7/180
f = -180/7 cm
f ≈ 25.7 cm
Therefore, the focal length of the concave mirror is approximately 25.7 cm.
Answer: 1)90÷11cm
Given,
Magnification (m) = 4.5
Object distance (u) = -20 cm (negative sign indicates that the object is placed in front of the mirror)
Let the focal length of the mirror be (f) cm.
Using the mirror formula,
1/f = 1/u + 1/v
where v is the image distance.
Magnification (m) = -v/u
Substituting the given values,
4.5 = -v/-20
v = 90 cm
Now, using the magnification formula,
m = -v/u = h'/h = 4.5
where h' is the height of the image and h is the height of the object.
h'/h = -v/u = 4.5
h'/h = -90/-20 = 4.5
h'/h = 9/2
Let the height of the object be (h) cm.
The height of the image (h') will be 4.5 times the height of the object.
h' = 4.5h = (9/2)h
Substituting the given value of object distance (u),
1/f = 1/-20 + 1/90
1/f = -7/180
f = -180/7 cm
f ≈ 25.7 cm
Therefore, the focal length of the concave mirror is approximately 25.7 cm.
Answer: 1)90÷11cm
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A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm?
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A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm?.
A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A real image formed by a concave mirror is 4.5 times the size of the object . If the mirror is 20 cm from the object, its focal length is? 1)90÷11cm 2)120÷11.cm 3)150÷11cm 4)180÷11cm?.
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