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Which of the following option of electromagnetic waves is in order of increasing frequency ?
Electromagnetic waves are ordered by increasing frequency as follows: Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays. Thus, 'microwaves, ultraviolet rays, x rays' is the correct order of increasing frequency.
The sum delivers $10^3 Wm^{-2} $ of electromagnetic flux to earth’s surface. The total power that is incident on a roof of dimension 8m x 20m will be
Bolometer is used to detect
A bolometer is an instrument for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It is most commonly used to detect infrared radiation, making option o1 (infrared rays) the correct answer.
Range of frequency of microwaves is about
Microwaves have a frequency range of approximately 3 GHz to 300 GHz. This frequency range falls within the electromagnetic spectrum and is used for various applications such as radar, satellite communication, and microwave ovens. Therefore, option o3 (3 GHz to 300 GHz) is correct.
SI unit of displacement current is
The SI unit of displacement current is the Ampere (A). Displacement current is a quantity appearing in Maxwell's equations, defined in terms of the rate of change of the electric displacement field. Therefore, option o2 (Ampere) is correct.
The frequencies of x rays, $ \gamma $ rays and ultraviolet rays are respectively p, q and r then
At room temperature, if the relative permitivity of water is 80 and the realtive permiability be 0.0222 then the velocity of light in water is----------m/s
The velocity of light in a medium is given by the formula $ v = rac{c}{ ext{n}} $, where $ c $ is the speed of light in vacuum and $ ext{n} $ is the refractive index of the medium. The refractive index can be calculated using $ n = rac{1}{ ext{sqrt}( ext{relative permittivity} imes ext{relative permeability})} $. Given the relative permittivity (80) and relative permeability (0.0222) of water, we find $ n = rac{1}{ ext{sqrt}(80 imes 0.0222)} ext{approx} 2.67 $. Therefore, the velocity of light in water is $ v = rac{3 imes 10^8}{2.67} ext{approx} 2.25 imes 10^8 ext{m/s} $. Hence, the correct option is $ 2.25 imes 10^8 ext{m/s} $.
When a plane electromagnetic wave travels in vaccum, the average electric energy density is given by ($E_o$ is the amplitude of the electric field)
In a plane electromagnetic wave , the electric field oscillates sinusoidaly at a frequency of $ 2.0 \times 10^10 Hz$. if the peak value of electric field is $60 Vm^{-1}$ the average energy density (in$ Jm^{-3}$) of the magnetic field of the wave will be (given $ \mu o = 4 \pi \times 10^{-7} T m/A $)
The average energy density of the magnetic field in an electromagnetic wave can be calculated using the formula: $$ u_B = rac{1}{2} rac{E_0^2}{c^2 imes rac{1}{ ext{μ}_0}} $$ Given that the peak electric field $E_0 = 60 ext{Vm}^{-1}$, $c = 3 imes 10^8 ext{ms}^{-1}$, and $ ext{μ}_0 = 4 ext{π} imes 10^{-7} ext{Tm/A}$, we find that: $$ u_B = rac{1}{2} rac{(60)^2}{(3 imes 10^8)^2 imes 4 ext{π} imes 10^{-7}} ext{Jm}^{-3}$$ Simplifying, we get: $$ u_B = rac{1}{2 ext{π}} imes 10^{-7} ext{Jm}^{-3} $$
Which of the following pairs of the component of space and time varying $ \vec E = ( E_x \hat i + Ey \hat j + Ez \hat k ) $ and $ \vec B = ( B_x \hat i + B y \hat j + Bz \vec k ) $ would generate a plane electromagnetic wave travelling in +ve y direction
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