An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained? Find the size and the nature of the image.
Download our app for free and get started
Object distance, u = -27 cm Object height, h = 7 cm Focal length, f = -18 cm According to the mirror formula,$\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$
$\frac{1}{\text{v}}=\frac{1}{\text{f}}-\frac{1}{\text{u}}$
$=\frac{-1}{18}+\frac{1}{27}-\frac{-1}{54}$
v = -54 cm The screen should be placed at a distance of 54 cm in front of the given mirror. Magnification, $\text{m}=-\frac{\text{Image Distance}}{\text{Object Distance}}=\frac{-54}{27}=-2$ The negative value of magnification indicates thet the image formed is real. Magnification, $\text{m}=\frac{\text{Hight of the image}}{\text{Hight of the object}}=\frac{\text{h}_\text{r}}{\text{h}}$ h' = 7 × (-2) = -14 cm. The negative value of image height indicates that the image formed is inverted.
$\frac{1}{\text{v}}=\frac{1}{\text{f}}-\frac{1}{\text{u}}$
$=\frac{-1}{18}+\frac{1}{27}-\frac{-1}{54}$
v = -54 cm The screen should be placed at a distance of 54 cm in front of the given mirror. Magnification, $\text{m}=-\frac{\text{Image Distance}}{\text{Object Distance}}=\frac{-54}{27}=-2$ The negative value of magnification indicates thet the image formed is real. Magnification, $\text{m}=\frac{\text{Hight of the image}}{\text{Hight of the object}}=\frac{\text{h}_\text{r}}{\text{h}}$ h' = 7 × (-2) = -14 cm. The negative value of image height indicates that the image formed is inverted.
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1View Solution
Draw the following diagram, in which a ray of light is incident on a concave/convex mirror, on your answer sheet. Show the path of this ray, after reflection, in each case.
- 2View SolutionA 2.0cm tall object is placed 40 cm from a diverging lens of focal length 15cm. Find the position and size of the image.
- 3View SolutionWhich mirror is used as a torch reflector? Draw a labelled diagram to show how a torch reflector can be used to produce a parallel beam of light. Where is the bulb placed in relation to the torch reflector?
- 4View SolutionState the type of mirror preferred as,
- Rear view mirror in vehicles.
- Shaving mirror. Justify your answer giving two reasons in each case.
- 5View SolutionDescribe with the help of a ray diagram the nature, size and position of the image formed when an object is placed at infinity (considerable distance) in front of a convex lens. State three characteristics of the image so formed.
- 6View SolutionA student uses a lens of focal length -50cm. What is the nature of the lens and its power?
- 7View SolutionTwo lenses have powers of (i) +2D and (ii) -4D. What is the nature and focal length of each lens?
- 8View SolutionAt what distance should an object be placed from a convex lens of focal length 18cm to obtain an image at 24cm from it on the other side? What will be the magnification produced in this case?
- 9View SolutionIf the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?
- 10View SolutionAn object is placed 20cm from (a) a converging lens, and (b) a diverging lens, of focal length 15cm. Calculate the image position and magnification in each case.