Question:
Electric field of plane electromagnetic wave propagating through a non-magnetic medium is given by $E=20 \cos \left(2 \times 10^{10} \mathrm{t}-200 \mathrm{x}\right) \mathrm{V} / \mathrm{m}$. The dielectric constant of the medium is equal to :
$\left(\right.$ Take $\mu_{\mathrm{r}}=1$ )
9
2
$\frac{1}{3}$
3
Correct Option: 1
Solution:
Speed of wave $=\frac{2 \times 10^{10}}{200}=10^{8} \mathrm{~m} / \mathrm{s}$
Refractive index $=\frac{3 \times 10^{8}}{10^{8}}=3$
Now refractive index $=\sqrt{\varepsilon_{\mathrm{r}} \mu_{\mathrm{r}}}$
$3=\sqrt{\varepsilon_{\mathrm{r}}(1)}$
$\Rightarrow \varepsilon_{\mathrm{r}}=9$
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- JEE Main
- Exam Pattern
- Previous Year Papers
- PYQ Chapterwise
- Physics
- Kinematics 1D
- Kinemetics 2D
- Friction
- Work, Power, Energy
- Centre of Mass and Collision
- Rotational Dynamics
- Gravitation
- Calorimetry
- Elasticity
- Thermal Expansion
- Heat Transfer
- Kinetic Theory of Gases
- Thermodynamics
- Simple Harmonic Motion
- Wave on String
- Sound waves
- Fluid Mechanics
- Electrostatics
- Current Electricity
- Capacitor
- Magnetism and Matter
- Electromagnetic Induction
- Atomic Structure
- Dual Nature of Matter
- Nuclear Physics
- Radioactivity
- Semiconductors
- Communication System
- Error in Measurement & instruments
- Alternating Current
- Electromagnetic Waves
- Wave Optics
- X-Rays
- All Subjects
- Physics
- Motion in a Plane
- Law of Motion
- Work, Energy and Power
- Systems of Particles and Rotational Motion
- Gravitation
- Mechanical Properties of Solids
- Mechanical Properties of Fluids
- Thermal Properties of matter
- Thermodynamics
- Kinetic Theory
- Oscillations
- Waves
- Electric Charge and Fields
- Electrostatic Potential and Capacitance
- Current Electricity
- Thermoelectric Effects of Electric Current
- Heating Effects of Electric Current
- Moving Charges and Magnetism
- Magnetism and Matter
- Electromagnetic Induction
- Alternating Current
- Electromagnetic Wave
- Ray Optics and Optical Instruments
- Wave Optics
- Dual Nature of Radiation and Matter
- Atoms
- Nuclei
- Semiconductor Electronics: Materials, Devices and Simple Circuits.
- Chemical Effects of Electric Current,
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