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XII_Phy_New_Chap-08 Electromagnetic Waves (55 A&R Items)
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Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516XII_Phy_New_Chap-08 _ ELECTROMAGNETIC WAVES
S# Correct Assertion Correct Reason
8.1 INTRODUCTION
Maxwell unified electricity and magnetism. His equations described these phenomena as interrelated
1
(electromagnetism).
Changing electric field induces magnetic field. Predicted by Maxwell's equations, a varying electric field
2
creates a magnetic field.
Displacement current addresses changing It supplements Ampere's Law to account for magnetic
3
electric fields. fields due to these changes.
Electromagnetic waves: propagating electric and Maxwell's equations describe coupled electric and
4
magnetic fields. magnetic fields traveling through space.
Light speed predicted by Maxwell's equations This strong correlation suggests light is an
5
matches measured speed. electromagnetic wave.
Hertz's experiments confirmed electromagnetic They provided experimental evidence for Maxwell's
6
waves. prediction.
Electromagnetic spectrum: vast range of It encompasses waves from very short gamma rays to long
7
wavelengths. radio waves.
8.2 DISPLACEMENT CURRENT
Displacement current arises from the rate of It represents a current-like effect due to varying electric
8
change of electric flux. fields, not charge flow.
Displacement current is introduced in Ampere- It accounts for magnetic fields generated by changing
9 Maxwell Law for accurate magnetic field electric fields.
prediction.
Displacement current complements conduction Together, they represent the total current source for
10
current (due to flowing charges). magnetic fields.
Displacement current explains magnetic fields in This validates Maxwell's prediction and highlights its
11 regions with no conduction current sources (e.g., importance.
between capacitor plates).
Displacement current creates symmetry between It allows a changing electric field to generate a magnetic
12
electricity and magnetism. field, mirroring Faraday's Law.
Displacement current paves the way for Time-varying electric and magnetic fields can induce each
13
electromagnetic waves. other, a foundation for electromagnetic waves.
8.3 ELECTROMAGNETIC WAVES
Electromagnetic waves are self-sustaining Unlike sound or water waves, EM waves require no medium
14 oscillations of electric and magnetic fields. for vibration, involving interacting electric and magnetic
fields.
Accelerated charges radiate electromagnetic An oscillating charge creates oscillating electric and
15 waves. magnetic fields that regenerate each other as the wave
propagates.
The speed of electromagnetic waves in a material These properties influence the interaction between the
16 depends on the material's permittivity and wave's electric and magnetic fields within the material,
permeability. affecting light propagation speed.
The speed of light in a vacuum is a constant This well-established value is independent of wavelength
17
299,792,458 m/s, experimentally verified. and serves as the standard for defining length.
Electromagnetic waves transport energy, While electrostatic and magnetostatic fields exert forces,
whereas electrostatic and magnetostatic fields they lack the wave-like properties that allow EM waves to
18
from stationary charges or steady currents do carry energy over long distances.
not.
Electromagnetic waves have electric and This configuration aligns with the concept of displacement
19 magnetic fields perpendicular to each other and current, a fundamental aspect of electromagnetic waves.
to the direction of propagation.
8.4 ELECTROMAGNETIC SPECTRUM
Microwaves heat food by transferring energy to The resonant frequency of microwaves matches that of
20 water molecules. water molecules, causing them to vibrate faster and
generate heat.
Infrared waves are called heat waves because Absorption of infrared radiation by water molecules
21 they are absorbed by water molecules. increases their kinetic energy, resulting in a rise in
temperature.
Visible light interacts with the human eye, while Our visual system is sensitive to a specific range of
22 ultraviolet light is invisible. wavelengths within the electromagnetic spectrum.
Ultraviolet light falls outside this range.
The ozone layer protects us from harmful The atmosphere absorbs most UV light in the ozone layer,
23
ultraviolet radiation. preventing it from reaching the Earth's surface.
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