To determine focal length of a concave mirror a student obtains the image of a well lit Distant object on a screen. To determine the focal length of the given concave mirror he needs to measure the distance between:

A student prepared an aqueous solution of CuS04 in beaker X and an aqueous solution of FeS04 in beaker Y. He then dropped some iron pieces in beaker X and some zinc pieces in beaker Y. after about 10 hours he observed that the solutions in X and Y respectively appear:

A student adds 4 mL of acetic acid to a test tube containing 4 ml of distilled water. He then shakes the test tube and leaves it to settle. after about, 10 minutes he observes:

To determine the focal length of a convex lens by obtaining a sharp image of a distant object we generally follow the following steps which are not in proper sequence.

(A) Hold the lens between the object and the screen

(B) Measure the distance between the lens and the screen

(C) Select a well lit distant object

(D) Place a screen opposite to the object on the lab table

(E) Adjust the position of the lens to form a sharp image

The correct sequence of these steps is:

A student traces the path of a ray of white light through a rectangular glass slab and marks the angles of incidence (i), refraction (r) and emergence (Le) as shown. Which angle or angles has he NOT marked correctly?