The part of human eye which controls the amount of light entering into it is:
Step 1: Identifying the structure. The iris is the part of the human eye that controls the size of the pupil and, in turn, regulates the amount of light entering the eye.
Step 2: Conclusion. Thus, the correct answer is option (A): Iris.
Lenses can form different types of images depending upon their focal length and position of object. A convex lens can create real, inverted or virtual, erect images, while a concave lens forms only virtual and diminished images. The focal length determines the power of lens. Convex lenses have positive focal length while concave lenses have negative focal length by convention. When lenses are placed together, their combined power is determined by the sum of their individual powers.
Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray incident on a concave mirror as shown:

