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Two towers on top of two hills are 40 km apart. The line joini
Physics Part-II
Physics Part-II

Class 12

NCERT

Publisher:
NCERT
Subject:
Physics
1

Chapter 1: Ray Optics and Optical Instruments

41 questions

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2

Chapter 2: Wave Optics

30 questions

Q1
Answer the following questions:
(a) 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?

(b) In what way is diffraction from each slit related to the interference pattern in a double-slit experiment?

(c) When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?

(d) 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.

(e) 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?
Q2
Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?
Q3
A parallel beam of light of wavelength 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first imum is at a distance of 2.5 mm from the centre of the screen. Find the width of the slit.
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3

Chapter 3: Dual Nature of Radiation and Matter

44 questions

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4

Chapter 4: Atoms

23 questions

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5

Chapter 5: Nuclei

38 questions

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6

Chapter 6: Semiconductor Electronics: Materials, Devices and Simple Circuits

25 questions

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Question
Easy
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Solving time: 3 mins

Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?

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Updated on: Jan 7, 2023

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Physics Part-II (NCERT)

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Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?
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Text SolutionText solutionverified iconVerified

Distance between the towers is 40km.
Height of the line joining the hills is .
Thus, the radial spread of the radio waves should not exceed 50 m.
Since the hill is located halfway between the towers, Fresnel’s distance can be obtained.
Aperture is
Fresnel’s distance is given by the relation,

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Answer the following questions:
(a) 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?

(b) In what way is diffraction from each slit related to the interference pattern in a double-slit experiment?

(c) When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?

(d) 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.

(e) 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?
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Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?
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A parallel beam of light of wavelength 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first imum is at a distance of 2.5 mm from the centre of the screen. Find the width of the slit.
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Question Text
Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?
Updated OnJan 7, 2023
TopicWave Optics
SubjectPhysics
ClassClass 12
Answer TypeText solution:1 Video solution: 9
Upvotes1004
Avg. Video Duration5 min