Advertisements
Advertisements
प्रश्न
A 3 cm tall object is placed at a distance of 7.5 cm from a convex mirror of focal length 6 cm. Find the location, size and nature of the image.
उत्तर
Given,
Height of the object AB, h1 = 3 cm
Distance of the object from the convex mirror, u = −7.5 cm
Focal length of the convex mirror (f) = 6 cm
Using mirror formula,
\[\frac{1}{v} + \frac{1}{u} = \frac{1}{f}\]
\[ \Rightarrow \frac{1}{v} = \frac{1}{f} - \frac{1}{u}\]
Putting values according to sign convention,
\[\frac{1}{v} = \frac{1}{6} - \frac{1}{( - 7 . 5)}\]
\[\frac{1}{v} = \frac{1}{6} + \frac{1}{7 . 5} = \frac{3}{10}\]
Magnification = m = \[- \frac{v}{u} = \frac{10}{7 . 5 \times 3}\]
\[\Rightarrow \frac{A'B'}{AB} = \frac{10}{7 . 5 \times 3}\]
\[ \Rightarrow A'B' = \frac{100}{75} = \frac{4}{3} = 1 . 33 \text{ cm }\]
Where A'B' is the height of the image.
Hence, the required location of the image is \[\frac{10}{3} \text{ cm }\] from the pole and image height is 1.33 cm. Nature of the image is virtual and erect.
APPEARS IN
संबंधित प्रश्न
Give a scientific reason:
Danger signals are red in colour.
Show with the help of a diagram, how unpolarised light from Sun gets linearly polarised by scattering.
Suppose you are inside the water in a swimming pool near an edge. A friends is standing on the edge. Do you find your friend taller or shorter than his usual height?
The image formed by a concave mirror
A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side on its principal axis, the intensity of light
A point object O is placed on the principal axis of a convex lens of focal length f = 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. An eye is placed 60 cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is
A concave mirror forms an image of 20 cm high object on a screen placed 5.0 m away from the mirror. The height of the image is 50 cm. Find the focal length of the mirror and the distance between the mirror and the object.
A cylindrical vessel, whose diameter and height both are equal to 30 cm, is placed on a horizontal surface and a small particle P is placed in it at a distance of 5.0 cm from the centre. An eye is placed at a position such that the edge of the bottom is just visible (see figure). The particle P is in the plane of drawing. Up to what minimum height should water be poured in the vessel to make the particle P visible?
Light is incident from glass (μ = 1.50) to water (μ = 1.33). Find the range of the angle of deviation for which there are two angles of incidence.
Fill in the blank and rewrite the completed statement:
Very fine particles mainly scatter ______ light.
Rainbow is the phenomenon due to ______.
State any one difference between a primary rainbow and a secondary rainbow.
A parallel beam of light of wavelength 5890 Å falls normally on a slit of width 0.2 mm. Find the distance between the first minima on the two sides of the central maximum of the diffraction pattern observed on a screen placed in the focal plane of a convex lens of focal length 50 cm. The lens is placed quite close to the slit.
| Case study: Mirage in deserts |
 |
|
To a distant observer, the light appears to be coming from somewhere below the ground. The observer naturally assumes that light is being reflected from the ground, say, by a pool of water near the tall object. Such inverted images of distant tall objects cause an optical illusion to the observer. This phenomenon is called mirage. This type of mirage is especially common in hot deserts. Based on the above facts, answer the following question : |
In an optical fibre, if n1 and n2 are the refractive indices of the core and cladding, then which among the following, would be a correct equation?
| Case study: Mirage in deserts |
|
|
To a distant observer, the light appears to be coming from somewhere below the ground. The observer naturally assumes that light is being reflected from the ground, say, by a pool of water near the tall object. Such inverted images of distant tall objects cause an optical illusion to the observer. This phenomenon is called mirage. This type of mirage is especially common in hot deserts. Based on the above facts, answer the following question: |
A diamond is immersed in such a liquid which has its refractive index with respect to air as greater than the refractive index of water with respect to air. Then the critical angle of diamond-liquid interface as compared to critical angle of diamond-water interface will
| Case study: Mirage in deserts |
|
|
To a distant observer, the light appears to be coming from somewhere below the ground. The observer naturally assumes that light is being reflected from the ground, say, by a pool of water near the tall object. Such inverted images of distant tall objects cause an optical illusion to the observer. This phenomenon is called mirage. This type of mirage is especially common in hot deserts. Based on the above facts, answer the following question: |
The following figure shows a cross-section of a ‘light pipe’ made of a glass fiber of refractive index 1.68. The outer covering of the pipe is made of a material of refractive index 1.44. What is the range of the angles of the incident rays with the axis of the pipe for the following phenomena to occur.
A passenger in an aeroplane shall ______.
