Question

An object is placed in front of a minor and an image is produced on a screen which has a magnification of -2.85 when the screen is placed 33.0 cm from the mirror. What type of mirror is being used? If the original object is erect and 14 cm tall, how tall is the image on the screen? What is the focal length of the mirror? If the screen is moved to 35 cm away from the mirror, how far from the mirrors surface must the object be placed to get a clear image on the screen?

Answer 1

Given data, Magnification, m-2.85 Image distance, v=33 cm Write the magnification formula to calculate the object distance. lu Substitute the values in the above equation. -2.85-33 lu 2.85 -11.58 cnm Since, the image distance and object distance both are positive, so the focal length will be positive Hence, it is a concave mirror

The height of the object h14 cm Write the magnification formula to calculate the image height na Substitute the values in the above equation -2.85- 14 壓= 2.85x14 - 39.9 cm Hence, the image height on the screen is 39.9 cm

Write the miror formula to calculate the focal length of miror. V lu Substitute the values in the above equation f 33 11.58 11158+33 f 33x11.58 f 8.57 cm Hence, the focal length of the mirror is 8.57 cm

The image distance v 35 cm Write the mirror formula to calculate the object distance v u Substitute the values in the above equation. 8.57 35 u u 8.57 35 1 35-8.57 u 35x8.57 u 11.35 cm Hence, the object is placed at a distance of 11.33 cm from the mirror.