FBISE, NCP & NBF-aligned resources for Classes 9–12
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Physics Chapter 9 : Topic 16
Applications of Polaroids
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Polaroids are used in sky photography mainly to:
Reasoning: Scattered sunlight from the sky becomes partially polarized. Polaroid filters block certain polarized components, reducing glare and improving contrast in photographs.
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The blue light scattered from the sky is useful in sky photography because it is:
Reasoning: Atmospheric scattering causes sunlight to become partially polarized, which allows polaroid filters to enhance sky images.
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A photographer rotates a polaroid filter while taking a sky photograph. The brightness changes because:
Reasoning: According to Malus’ law, transmitted intensity depends on the angle between the transmission axis of the polaroid and the polarization direction of light.
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A polaroid filter makes the sky appear darker in photographs because it:
Reasoning: The filter absorbs certain polarization components of scattered sunlight, reducing brightness and increasing contrast.
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Which property of light allows polaroids to be used in sky photography?
Reasoning: Polaroids work because light waves are transverse and can be polarized.
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In sky photography, the best orientation of a polaroid filter is usually determined by:
Reasoning: The filter is rotated to reduce unwanted polarized scattered light and obtain a clearer image.
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Polaroid sunglasses and polaroid filters used in photography work on the same principle because both:
Reasoning: A polaroid allows vibrations along one axis and absorbs vibrations perpendicular to it.
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The use of polaroids in stress analysis is based on the phenomenon of:
Reasoning: Photoelasticity is the property of transparent materials to become birefringent when stressed.
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In stress analysis, transparent materials are placed between crossed polaroids to observe:
Reasoning: Stressed transparent materials show interference patterns between crossed polaroids.
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A transparent plastic model placed between two crossed polaroids shows bright and dark patterns because:
Reasoning: Stress creates optical anisotropy, causing birefringence and producing interference patterns.
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In photoelastic stress analysis, regions of different colors indicate:
Reasoning: The interference colors depend on the amount and distribution of stress in the material.
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Engineers use polaroids for stress analysis because they can:
Reasoning: Photoelastic methods allow visualization of internal stresses in transparent models without damaging them.
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When a transparent material is stressed, it becomes:
Reasoning: Stress changes the optical properties of the material, making it birefringent.
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The main purpose of crossed polaroids in stress analysis is to:
Reasoning: Crossed polaroids allow analysis of the phase differences produced by stressed materials.
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A plastic model shows more colorful fringes at a certain region. This indicates:
Reasoning: Higher stress causes greater birefringence, producing more noticeable interference fringes.
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In photoelastic experiments, a material is usually placed between:
Reasoning: Crossed polaroids reveal the stress-induced changes in polarization of transmitted light.
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If a transparent material has no internal stress, the arrangement of crossed polaroids will generally produce:
Reasoning: Without stress-induced birefringence, light remains blocked by crossed polaroids.
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Stress analysis using polaroids is especially useful in designing:
Reasoning: Engineers use photoelastic techniques to locate stress points in models of mechanical structures.
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The colored patterns observed in photoelasticity are produced due to:
Reasoning: Stress splits light into two components with different speeds, causing interference and colors.
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A polaroid filter in a camera reduces glare because it:
Reasoning: Polaroids selectively transmit one component of polarized light and absorb the perpendicular component.
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The ability of stressed transparent materials to show colors between polaroids is called:
Reasoning: Photoelasticity is the stress-induced optical effect used for stress visualization.
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A photographer uses a polaroid filter while capturing clouds. The main advantage is:
Reasoning: The filter reduces polarized glare from the sky, making clouds appear clearer.
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The stress distribution in a material can be studied using polaroids because stress:
Reasoning: Mechanical stress changes refractive indices along different directions, producing birefringence.
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Which statement about polaroids is correct?
Reasoning: Only transverse waves can be polarized, and light is a transverse electromagnetic wave.
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In engineering laboratories, polaroids help engineers to:
Reasoning: Photoelastic stress analysis reveals internal stress patterns that are otherwise invisible.
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