An image formed on a screen is always?

A ray of light traveling from glass into ethyl alcohol is incident at the boundary at an angle of incidence 30\(^o\). Calculate the angle of refraction.

[Refractive index of glass =1.5; refractive index of ethyl alcohol = 1.36]
 

You are provided with a metre rule, lens, screen, ray box, and other necessary apparatus.

i. Set up the experiment as shown in the diagram above. Measure and record the diameter a\(_{0}\), of the illuminated object.

ii. Place the object at a distance x= 25cm from the lens. Adjust the screen until a sharp image is obtained on the screen.

iii. Measure and record the diameter, a, of the image.

iv. Measure and record the distance v between the lens and the screen.

v. Evaluate y = P = \(\frac{1+y^{2}}{y}\) and T= x+v.

vi. Repeat the procedure for x = 30cm, 35cm, 40cm and 45cm. In each case, determine the corresponding values of a,v,y, P and T.

vii. Tabulate your results.

viii. Plot a graph of P on the vertical axis against T on the horizontal axis starting both axes from the origin (0,0).

ix. Determine the slope, s, of the graph.

x. Determine the intercept, c, on the horizontal axis.

xi Evaluate K = \(\frac{c}{2}\)

xii. State two precautions taken to ensure accurate results.

(b)i.  Explain the statement, the focal length of a converging lens is 20cm.

ii. An object is placed at a distance x from a converging lens of focal length 20cm. If the magnification of the real image is 5, calculate the value of x.

A man stands 4m in front of a plane mirror. If the mirror is moved 1m towards the man, the distance between him and his new image is?

The inside portion of part of a hollow metal sphere of diameter 20cm is polished. The portion will therefore form a?