uR Spot adjacent to it is imm D) 225 mm E) 450 mm 25. A ray of light strikes a water-glass
interface at an angle of incidence of 35°. The angle of refraction is 35* Waler Glass A) 594 B)
19.7 C) 40.3 D) 22.1 E) 30.6 26. A real object is 42.1 cm from a negative lens that has a focal
length of 25.6 cm. The object is 2.45 mm high. The height and orientation of the image are A)
6.4 mm and erect. B) 0.38 mm and erect C) 0.93 mm and erect. D) 3.8 mm and inverted E) None
of these is correct. 27. Light of wavelength 450 nm is incident on a narrow slit. The diffraction
pattern is observed on a screen 5.0 m from the slit., and the central maximum is observed to have
a width of 22 cm. What is the width of the slit? 28. An object 5.0 cm tall is placed 15 cm in front
of a converging lens of focal length 30 cm. The final image size is A) 3.3 cm B) 10 cm C) 7.5 cm
D) 2.5 cm E) 5.0 cm itive lens of focal length 40 cm is placed 20 cm behind a negative lens of
focal length-80 cm. An object is placed 240 cm in front of the negative lens. The final image
distance relative to the positive lens is A) 80 cm B) -40 cm C)-80 cm D) -56 cm E) 56 cm 30.
The critical angle for light rays passing from flint glass (n- 1.70) into air is about A) 90° B)
3.4° C) 36 D) 44 E) 54°
Solution
25) using the snell's law we have
n1 sin1 = n2 sin 2
1.33* sin 35 = 1.5* sin b
b = 30.6 o
so option E) is the correct answer
30) n1 sin a = n2 sin b
1.7 * sin i = 1* sin 90
i = 36 o
so option C) is the correct answer