Advertisements
Advertisements
Question
Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification?
Solution
The justification is that in ordinary optical instruments, the size of the aperture involved is much larger than the wavelength of the light used.
APPEARS IN
RELATED QUESTIONS
Estimate the distance for which ray optics is good approximation for an aperture of 4 mm and wavelength 400 nm.
In a single slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band?
In what way is diffraction from each slit related to the interference pattern in a double-slit experiment?
Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily?
In a single slit diffraction experiment, when tiny circular obstacle is placed in path of light from a distance source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?
State two points of difference between the interference patterns obtained in Young’s double slit experiment and the diffraction pattern due to a single slit.
Will the diffraction effects from a slit be more or less clearly visible if the slit-width is increased?
Answer the following question.
In a single slit diffraction experiment, the width of the slit is increased. How will the (i) size and (ii) intensity of central bright band be affected? Justify your answer.
The focal length of a this lens in vacuum is f. If the material of the lens has µ = 3/2, its focal length when immersed in water refractive index 4/3 will
