Answer Happy

R. RCT 1 h 156. A magnifier for reading is in the form of a glass half cylinder of radius R and refractive index n. To use it, you place the flat side on the page you're trying to read, and several lines of text ap- This horizontal distance is R. pear magnified. Find an expression for the magnification this device h' provides. Hint: With the object (the text) right at the surface of the mag- nifier, you can't treat the half cylin- der as a thin lens. Instead, consult Fig. 31.36, which shows an arrow FIGURE 31.36 The figure as a small object being magnified. shows one ray emerging Assume the arrow's length h is horizontally from small enough that the horizontal the arrowhead and distance from the arrowhead to the refracting at the surface curved surface in Fig. 31.36 is ap- of the magnifier. Also proximately the radius R, and that shown is the normal to the angles a and y are therefore the glass-air interface, small enough that you can use the drawn from the center (C) and extending radially small-angle approximation for their outward. sines and tangents.