In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Downloads of CBSE Class 12 Physics Chapter 8 Electromagnetic Waves Case Study and Passage-Based Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve NCERT Class 12 Physics Case Study Questions Electromagnetic Waves to know their preparation level.
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In CBSE Class 12 Physics Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
Electromagnetic Waves Case Study Questions With Answers
Here, we have provided case-based/passage-based questions for Class 12 Physics Chapter 8 Electromagnetic Waves
Case Study/Passage-Based Questions
Case Study 1: Read the passage given below and answer the following questions from 1 to 4
In an electromagnetic wave both the electric and magnetic fields are perpendicular to the direction of propagation, that is why electromagnetic waves are transverse in nature. Electromagnetic waves carry energy as they travel through space and this energy is shared equally by the electric and magnetic fields. The energy density of electromagnetic waves is the energy in a unit volume of the space through which the wave travels.
The fundamental particle in an electromagnetic wave is
(a) photon (b) electron
(c) phonon (d) proton
Answer: (a) Photon is the fundamental particle in an electromagnetic wave.
For a wave propagating in a medium, identify the property that is independent of the others.
(a) velocity
(b) wavelength
(c) frequency
(d) all these depend on each other
Answer: (c) – Frequency u remains unchanged when a wave propagates from one medium to another. Both wavelength and velocity get changed.
The electric and magnetic fields of an electromagnetic waves are
(a) in opposite phase and perpendicular to each other
(b) in opposite phase and parallel to each other
(c) in phase and perpendicular to each other
(d) in phase and parallel to each other
Answer: (c) – The electric and magnetic fields of an electromagnetic wave are in phase and perpendicular to each other.
Case Study 2: An electromagnetic wave transports linear momentum as it travels through space. If an electromagnetic wave transfers a total energy U to a surface in time t, then the total linear momentum delivered to the surface is p = U/c. When an electromagnetic wave falls on a surface, it exerts pressure on the surface. In 1903, the American scientists Nichols and Hull succeeded in measuring radiation pressures of visible light where others had failed, by making a detailed empirical analysis of the ubiquitous gas heating and ballistic effects.
The pressure exerted by an electromagnetic wave of intensity I(W m–2) on a non-reflecting surface is (c is the velocity of light)
(a) Ic (b) Ic2 (c) I/c (d) I/c2
Answer: (c) – Pressure exerted by an electromagnetic radiation,P= I/C
Light with an energy flux of 18 W/cm2 falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is
(a) 2 N/m2 (b) 2 × 10–4 N/m2
(c) 6 N/m2 (d) 6 × 10–4 N/m2
Answer: (d) – Solve it
A point source of electromagnetic radiation has an average power output of 1500 W. The maximum value of the electric field at a distance of 3 m from this source (in V m–1) is
(a) 500 (b) 100
(c) 500/3 (d) 250/3
Answer: (b) – Solve it
Case Study 3: In Chapter 8, Electromagnetic Waves, we discussed the production and properties of electromagnetic waves. One key concept we reviewed is Maxwell’s equations which form the foundation of electromagnetic theory. To summarize, the equations describe how electric charges and currents create electric and magnetic fields. These fields interact to form electromagnetic waves. For instance, when an oscillating charge accelerates, it produces an oscillating electric field. This electric field, in turn, creates an oscillating magnetic field, and these two interlinked fields propagate together through space at the speed of light, forming an electromagnetic wave. The speed of light in a vacuum is a constant, approximately 3 x 10^8 meters per second. This principle helps us understand a range of phenomena, from the operation of antennas and transmitters to the propagation of light and radio signals through space.
What are the four Maxwell’s equations used for?
A) They describe how electric charges create electric fields only.
B) They describe how electric charges and currents create electric and magnetic fields.
C) They describe how magnetic fields are created by electric currents only.
D) They describe the interaction between light and matter.
How is an electromagnetic wave formed?
A) An oscillating charge creates an oscillating magnetic field, which then produces an electric field.
B) An accelerating charge creates an oscillating electric field, which then produces an oscillating magnetic field.
C) An electric field creates a magnetic field, which then produces a charge.
D) A magnetic field and an electric field exist independently of each other and do not interact.
What is the approximate speed of light in a vacuum?
A) 3 x 10^8 meters per second
B) 3 x 10^6 meters per second
C) 3 x 10^4 meters per second
D) 3 x 10^2 meters per second
Answers:
- B) They describe how electric charges and currents create electric and magnetic fields.
- B) An accelerating charge creates an oscillating electric field, which then produces an oscillating magnetic field.
- A) 3 x 10^8 meters per second
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