Case Study 1: Reflection of Light
Reflection is the bouncing back
of light rays when they strike a surface. There are two types of reflection:
specular reflection, where light reflects off a smooth surface, and
diffuse reflection, where light reflects off a rough surface. The law of
reflection states that the angle of incidence is equal to the angle of
reflection.
Questions:
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What is the angle of incidence if the angle of
reflection is 30°?
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a) 15°
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b) 30°
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c) 60°
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d) 90°
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In which type of reflection do parallel rays remain
parallel after reflection?
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a) Diffuse reflection
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b) Specular reflection
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c) Total internal reflection
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d) None of the above
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Which of the following is an example of specular
reflection?
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a) Light reflecting off a rough wall
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b) Light reflecting off a calm water surface
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c) Light reflecting off a piece of paper
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d) Light scattering in fog
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The law of reflection applies to:
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a) Only plane mirrors
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b) Only curved mirrors
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c) All types of surfaces
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d) Only smooth surfaces
Answers:
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b) 30°
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b) Specular reflection
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b) Light reflecting off a calm water surface
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c) All types of surfaces
Case Study 2: Refraction of Light
Refraction is the bending of
light as it passes from one medium to another due to a change in its speed. The
amount of bending depends on the indices of refraction of the two media, which
is described by Snell's Law. When light travels from a medium with a lower
refractive index to one with a higher refractive index, it bends towards the
normal.
Questions:
-
If light travels from air (n = 1) into water (n =
1.33), what happens to the speed of light?
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a) It increases
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b) It decreases
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c) It remains the same
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d) It becomes infinite
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What is the formula for Snell's Law?
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a) n1sin(θ1) = n2sin(θ2)
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b) n1 + n2 = sin(θ1 + θ2)
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c) θ1 + θ2 = 90°
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d) n1/θ1 = n2/θ2
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When light passes from a denser to a rarer medium, it:
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a) Bends towards the normal
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b) Bends away from the normal
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c) Remains straight
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d) Stops
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The critical angle for total internal reflection
occurs when:
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a) Light travels from a denser to a rarer medium
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b) Light travels from a rarer to a denser medium
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c) The angle of incidence is 90°
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d) None of the above
Answers:
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b) It decreases
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a) n1sin(θ1) = n2sin(θ2)
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b) Bends away from the normal
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a) Light travels from a denser to a rarer medium
Case Study 3: Lenses and Their Applications
Lenses are optical devices made
of transparent material that refract light to converge or diverge beams. There
are two main types of lenses: convex (converging) lenses and concave
(diverging) lenses. Convex lenses focus light rays to a point, while concave
lenses spread light rays apart.
Questions:
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What type of lens is used in a magnifying glass?
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a) Concave lens
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b) Convex lens
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c) Plano-convex lens
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d) Biconcave lens
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In a convex lens, the point where light rays converge
is called:
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a) Focal point
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b) Principal focus
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c) Optical center
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d) Radius of curvature
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What is the focal length of a concave lens?
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a) Positive
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b) Negative
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c) Zero
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d) Infinity
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Which type of lens is used to correct nearsightedness
(myopia)?
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a) Convex lens
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b) Concave lens
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c) Cylindrical lens
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d) Bifocal lens
Answers:
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b) Convex lens
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a) Focal point
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b) Negative
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b) Concave lens
Case Study 4: Optical Instruments
Optical instruments such as
microscopes and telescopes utilize lenses and mirrors to magnify images. The
compound microscope uses two convex lenses to achieve high magnification,
while the refracting telescope uses a combination of a convex objective
lens and a convex eyepiece lens to magnify distant objects.
Questions:
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What is the main purpose of a compound microscope?
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a) To magnify distant objects
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b) To magnify small objects
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c) To correct vision
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d) To reflect light
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In a refracting telescope, the role of the eyepiece
lens is to:
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a) Collect light
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b) Focus the light
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c) Magnify the image
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d) Both b and c
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Which type of lens is used as the objective lens in a
compound microscope?
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a) Convex lens
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b) Concave lens
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c) Cylindrical lens
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d) Bifocal lens
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The total magnification of a microscope is the product
of:
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a) The focal lengths of the lenses
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b) The magnification of the objective and eyepiece lenses
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c) The distances from the object to the lenses
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d) The angles of incidence and refraction
Answers:
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b) To magnify small objects
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d) Both b and c
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a) Convex lens
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b) The magnification of the objective and eyepiece
lenses
Case Study 5: Wavefronts and Rays
In optics, a wavefront is a
surface over which an optical wave has a constant phase. The concept of rays is
used to represent the direction of light propagation. The interaction of
wavefronts and rays helps explain phenomena such as diffraction, interference,
and the formation of images.
Questions:
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What is a wavefront?
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a) A line of light
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b) A surface connecting points of equal phase
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c) A point where light converges
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d) A reflection of light
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Rays in optics represent:
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a) The speed of light
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b) The direction of light propagation
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c) The energy of light
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d) The frequency of light
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Which of the following best describes a plane
wavefront?
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a) A wavefront that converges
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b) A wavefront that diverges
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c) A wavefront that is flat and extends infinitely
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d) A wavefront that is circular
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The principle of superposition applies to:
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a) Only reflection
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b) Only refraction
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c) Only interference
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d) All types of wave interactions
Answers:
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b) A surface connecting points of equal phase
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b) The direction of light propagation
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c) A wavefront that is flat and extends infinitely
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d) All types of wave interactions