Physics
Physical Optics
Page 11 of 17
#81 Two thin lenses of focal lengths \( f_1 \) and \( f_2 \) are placed in contact. The combined focal length \( F \) is given by:
A) \( F = f_1 + f_2 \)
B) \( F = f_1 - f_2 \)
C) \( \frac{1}{F} = \frac{1}{f_1} + \frac{1}{f_2} \)
D) \( F = \frac{f_1 f_2}{f_1 + f_2} \)
#82 Spherical aberration in a lens can be reduced by:
A) Using a combination of lenses
B) Using monochromatic light
C) Using a diaphragm
D) Both A and C
#83 Chromatic aberration occurs because the focal length of a lens depends on the:
A) Thickness of the lens
B) Diameter of the lens
C) Refractive index of the lens material
D) Wavelength of light
#84 An achromatic doublet is designed to correct for:
A) Spherical aberration
B) Chromatic aberration
C) Coma
D) Astigmatism
#85 The minimum distance between an object and its real image formed by a convex lens is:
A) \( f \)
B) \( 2f \)
C) \( 4f \)
D) Zero
#86 For a simple microscope (magnifying glass), the angular magnification is maximum when the image is formed at the:
A) Near point
B) Far point
C) Center of curvature
D) Focal point
#87 The phenomenon of interference is based on
A) Conservation of energy
B) Conservation of momentum
C) Wave nature of light
D) Particle nature of light
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