If an electromagnetic wave of frequency f = 3 MHz passes from vacuum into a dielectric medium with relative permittivity K= 4.0, then:
1. | wavelength is 2 times and frequency becomes half |
2. | wavelength is half and frequency remains unchanged |
3. | wavelength and frequency both remain unchanged |
4. | None of the above |
The condition under which a microwave oven heats up a food item containing water molecules most efficiently is:
1. | the frequency of the microwave must match the resonant frequency of the water molecules. |
2. | the frequency of the microwave has no relation to the natural frequency of water molecules. |
3. | microwave are heatwaves, so always produce heating. |
4. | infrared waves produce heating in a microwave oven. |
The decreasing order of the wavelength of infrared, microwave, ultraviolet and gamma rays is:
1. | Gamma rays, ultraviolet, infrared, microwaves |
2. | Microwaves, gamma rays, infrared, ultraviolet |
3. | Infrared, microwave, ultraviolet, gamma rays |
4. | Microwave, infrared, ultraviolet, gamma rays |
The electric field part of an electromagnetic wave in a medium is represented by :
1. | Moving along y-direction with frequency \(2\pi\times 10^6~Hz\) and wavelength 200 m. |
2. | Moving along +x-direction with frequency \(10^6~Hz\) and wavelength 100 m. |
3. | Moving along +x-direction with frequency \(10^6~Hz\) and wavelength 200 m. |
4. | Moving along - x-direction with frequency \(10^6~Hz\) and wavelength 200 nm. |
A parallel plate capacitor consists of two circular plates each of radius \(2~\text{cm}\), separated by a distance of \(0.1~\text{mm}\). If the voltage across the plates is varying at the rate of \(5\times10^{13}~\text{V/s}\), then the value of displacement current is:
1. \(5.50~\text{A}\)
2. \(5.56\times 10^{2}~\text{A}\)
3. \(5.56\times 10^{3}~\text{A}\)
4. \(2.28\times 10^{4}~\text{A}\)
In an electromagnetic wave:
1. | power is transmitted along the magnetic field. |
2. | power is transmitted along the electric field. |
3. | power is equally transferred along with the electric and magnetic fields. |
4. | power is transmitted in a direction perpendicular to both the fields. |
The frequency \(1057~\text{MHz}\) of radiation arising due to electron transition between two close energy levels in hydrogen belongs to:
1. radio waves
2. infrared waves
3. microwaves
4. \(\gamma-\)rays
A larger parallel plate capacitor, whose plates have an area of 1 , separated from each other by 1 mm, is being charged at a rate of 25.8 V/s. If the plates have dielectric constant 10, then the displacement current at this instant is:
1. 25
2. 11
3. 2.2
4. 1.1
A parallel plate capacitor with plate area \(A\) and separation between the plates \(d\), is charged by a source having current \(i\) at some instant. Consider a plane surface of area \(A/2\) parallel to the plates and drawn symmetrically between the plates. The displacement current through this area is:
1. \(i\)
2. \(i/2\)
3. \(i/4\)
4. \(i/8\)
The sun delivers of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions 8 m20 m will be:
1.
2.
3.
4. 1.6