NEET Physics Questions: Electromagnetic Waves
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Question bank:
An insulater ared in a transmission line has dierectrie unstant equal to 0.25 What is the velocity factor of the transmission line ?
No explanation available.
The velocity of e.m. waves in a medium is $ 2.5 \times 10 ^ 8 ms^ {-1}$ what is the dielectric constant of the medium ?
No explanation available.
How long will it take to transmit the information 30km away in space ?
No explanation available.
When electromagnetic waves enter the ionised layer of ionosphere, the relative permitting of the ionised layer
No explanation available.
In which of the following media the wave propagation occurs with out attention ?
No explanation available.
The dimensional formula of $ l_0 E_0$ is
No explanation available.
A plane electromagnetic wave is incident on a material surface. The wave delivers momentum P and energy E
When a plane electromagnetic wave is incident on a material surface, it delivers both momentum and energy. The energy carried by the wave is related to the intensity of the wave, and the momentum is related to the energy by the equation $P = rac{E}{c}$, where $c$ is the speed of light. Therefore, both momentum and energy are non-zero. Hence, the correct option is $P
eq 0, E
eq 0$.
If $ V_\gamma , V_x and V_m $ are the velocity of the v rays, x rays, micro waves respectively in space, then
The velocity of electromagnetic waves in a vacuum is the speed of light, which is approximately $3 imes 10^8$ meters per second. This speed is the same for all types of electromagnetic waves, including gamma rays ($V_ ext{γ}$), X-rays ($V_ ext{x}$), and microwaves ($V_ ext{m}$). Therefore, $V_ ext{γ} = V_ ext{x} = V_ ext{m}$.
According to Maxwell, a changing electric field produces
According to Maxwell's equations, a changing electric field produces a magnetic field. This relationship is described by the Maxwell-Ampère law: $$
abla imes extbf{E} = - rac{ ext{d} extbf{B}}{ ext{d}t}$$ which indicates that a time-varying electric field generates a magnetic field.
An electromagnetic wave going through vaccum is described by $ E= E_o sin (kx - \omega t ) $ Which of the following is independent of the wavelength?
Which of the following have zero average value in a plane electromagnetic wave?
In a plane electromagnetic wave, the electric field and magnetic field oscillate sinusoidally with time. The average value of a sinusoidal function over a complete cycle is zero. Therefore, the average value of the electric field ( extbf{E}) in a plane electromagnetic wave is zero.
If the relative permeability and dielectric constant of a given medium are equal to $ l_r \,and K $ respectively, then the refractive index of the medium is equal to__________
The refractive index \( n \) of a medium is given by the square root of the product of its relative permeability \( \mu_r \) and dielectric constant \( \kappa \). Mathematically, \( n = \sqrt{\mu_r \kappa} \). Hence, the correct option is \( \sqrt{\mu_r \kappa} \).
Astraonomers have found that electromagnetic waves of wavelength 21cm are continuously reaching the Earth’s surface . Calculate the frequency of this radia- tion $ ( c = 3 \times 10^8 m/s) $
To find the frequency \( f \) of the radiation, we use the relation \( c = \lambda f \), where \( c \) is the speed of light, \( \lambda \) is the wavelength, and \( f \) is the frequency. Given \( \lambda = 21 \text{ cm} = 0.21 \text{ m} \) and \( c = 3 \times 10^8 \text{ m/s} \), we can calculate the frequency as:
\[ f = \frac{c}{\lambda} = \frac{3 \times 10^8}{0.21} = 1.428 \times 10^9 \text{ Hz} = 1.428 \text{ GHz} \] Hence, the correct option is 1.428 GHz.
Electric field in an electromagnetic wave is given by $ E = 50 sin \omega ( t - (x/c )) NC^{-1} $ intensity of this wave is ___________ $Wm^-2$
No explanation available.
The amplitude of the electric field in a parallel beam of light of intensity $ 2.0 Wm-^2$ is
No explanation available.