Light questions | form three Physics

(a) (i) Explain the terms opaque and translucent and give an example of each.
(ii) Danger signs along the road as well as tail and brake lamps of motor vehicles rear are painted red. Briefly explain the reason behind.
(b) What is the basic difference between real and virtual image as formed by curved surfaces.
(c) (i) Give two reasons why convex mirror are used as driving mirror?
(ii) A convex mirror of focal length 18cm produces an image on its axis 6cm away from the mirror. Calculate the position of the object.

Answer / Solution

UNSOLVED

The aim of this experiment is to determine the refractive index, n of a glass block

1. Fix the plane sheet of paper provided on the soft board using optical pins
2. Place the glass block on the sheet of paper so that the largest face is topmost as shown in the Figure 2 and trace out the outline of the glass block.

100. Stick pins P1 and P2in the soft board in such a way that the angle of incidence is 25° and make sure that AO is less than one third of AB.

500. Place pins P3 and P4so that they may appear to be in the line with the images of P1 and P2 as observed through the face CD of the block.

5. Remove the block and trace the ray through it
6. Measure and record the distance L
7. Replace the block and repeat the procedures (c) to (f) for the angle of incidence  i=35°, 45°,55° and 65°.
8. Tabulate your results including including the values of  and 
9. Plot a graph of against .
10. Determine the slope ,s of your graph and the intercept  C₁ on the axis.
11. Find the values of “n”  from the relation and the breadth b of the glass block from the relation

Answer / Solution

UNSOLVED

What makes a coin inside the water at the bottom of a vessel appear to rise when viewed from above?
A Reflection of light. B Refraction of light. C Mirage of light.
D Spectrum of light. E Diffraction of light.

Answer / Solution

UNSOLVED

(i) Explain what happens when a white light is incident on a triangular glass prism.
(ii) Calculate the angle of refraction in the glass if light is incident in the air at 40° on a plane glass surface of refractive index of 1.52.

Answer / Solution

UNSOLVED

1. Derive an expression, by using the mirror formula where,  m stand for
   magnification of the image formed and other symbols carry their usual meaning.
2. A concave mirror has a focal length of 40 cm. How far from the mirror must an object be placed to produce an image that is
   (i) twice the size of the object.
   (ii) half the size of the object.

Answer / Solution

UNSOLVED