Q. A beam of light enters a prism with an angle of 60 degrees. If the refractive index of the prism is 1.5, what is the angle of refraction inside the prism?
A.30 degrees
B.45 degrees
C.60 degrees
D.90 degrees
Solution
Using Snell's law, sin(θ2) = sin(60)/1.5, we find θ2 = 30 degrees.
Q. A beam of light enters a prism with an angle of incidence of 45 degrees. If the refractive index of the prism is 1.5, what is the angle of refraction inside the prism?
Q. A beam of light in glass (n=1.5) strikes the glass-air interface at an angle of 60°. Will total internal reflection occur?
A.Yes
B.No
C.Only if the angle is increased
D.Only if the angle is decreased
Solution
To determine if total internal reflection occurs, we first find the critical angle using sin(θc) = 1/n = 1/1.5, which gives θc ≈ 41.8°. Since 60° > 41.8°, total internal reflection will not occur.
Q. A beam of light passes through a thin convex lens with a focal length of 15 cm. If the object is placed 30 cm from the lens, what is the image distance?
A.10 cm
B.15 cm
C.20 cm
D.30 cm
Solution
Using the lens formula, 1/f = 1/v - 1/u; here, f = 15 cm and u = -30 cm. Thus, 1/v = 1/15 + 1/30 = 1/10, giving v = 10 cm.
Q. A concave mirror has a focal length of 10 cm. An object is placed 30 cm in front of the mirror. Where will the image be formed?
A.10 cm
B.15 cm
C.20 cm
D.30 cm
Solution
Using the mirror formula, 1/f = 1/v + 1/u, where f = -10 cm (concave mirror), u = -30 cm. Solving gives v = -15 cm, which means the image is formed 15 cm in front of the mirror.
Q. A concave mirror produces a virtual image of an object placed 10 cm in front of it. If the focal length of the mirror is 5 cm, what is the distance of the image from the mirror?
A.5 cm
B.10 cm
C.15 cm
D.20 cm
Solution
Using the mirror formula, 1/f = 1/v + 1/u. Here, f = -5 cm (concave mirror), u = -10 cm. Solving gives v = -10 cm.
Q. A convex lens has a focal length of 20 cm. If an object is placed at a distance of 30 cm from the lens, what is the distance of the image from the lens?
A.60 cm
B.15 cm
C.30 cm
D.10 cm
Solution
Using the lens formula 1/f = 1/v - 1/u, we find v = 60 cm.
Q. A convex lens has a focal length of 20 cm. If an object is placed at a distance of 40 cm from the lens, what is the distance of the image from the lens?
A.20 cm
B.40 cm
C.60 cm
D.80 cm
Solution
Using the lens formula 1/f = 1/v - 1/u, where f = 20 cm and u = -40 cm, we find v = 20 cm. The image is formed at 20 cm on the opposite side.
Q. A double convex lens has a focal length of 10 cm. If it is made of a material with a refractive index of 1.5, what is the radius of curvature of each surface assuming they are equal?
A.15 cm
B.20 cm
C.25 cm
D.30 cm
Solution
Using the lens maker's formula, R = 2f(n-1) = 2*10*(1.5-1) = 20 cm.
Q. A fiber optic cable uses total internal reflection. If the refractive index of the core is 1.5 and that of the cladding is 1.4, what is the critical angle?