Advertisements
Advertisements
प्रश्न
In a microwave oven, the food is kept in a plastic container and the microwaves is directed towards the food. The food is cooked without melting or igniting the plastic container. Explain.
उत्तर
The natural frequency of water matches the frequency of microwave. This is the reason that food containing water gets cooked. The natural frequency of the plastic container does not match the frequency of microwave. So, the plastic container is not damaged.
APPEARS IN
संबंधित प्रश्न
The amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is B0 = 510 nT. What is the amplitude of the electric field part of the wave?
About 5% of the power of a 100 W light bulb is converted to visible radiation. What is the average intensity of visible radiation
(a) at a distance of 1 m from the bulb?
(b) at a distance of 10 m?
Assume that the radiation is emitted isotropically and neglect reflection.
In the study of a photoelectric effect the graph between the stopping potential V and frequency v of the incident radiation on two different metals P and Q is shown below:
(i) Which one of the two metals has higher threshold frequency?
(ii) Determine the work function of the metal which has greater value.
(iii) Find the maximum kinetic energy of electron emitted by light of frequency 8 × 1014 Hz for this metal.
If the amplitude of the magnetic field is 3 x 10-6 T, then amplitude of the electric field for a electromagnetic waves is ______.
Consider an oscillator which has a charged particle oscillating about its mean position with a frequency of 300 MHz. The wavelength of electromagnetic waves produced by this oscillator is ______.
Which of the following is an electromagnetic wave?
Write notes on Gauss' law in magnetism.
Give two uses of UV radiation.
Discuss the Hertz experiment.
A pulse of light of duration 10-6 s is absorbed completely by a small object initially at rest. If the power of the pulse is 60 x 10-3 W, calculate the final momentum of the object.
Let an electromagnetic wave propagate along the x-direction, the magnetic field oscillates at a frequency of 1010 Hz and has an amplitude of 10-5 T, acting along the y – direction. Then, compute the wavelength of the wave. Also write down the expression for the electric field in this case.
Which of these mechanisms can be used to produce electromagnetic waves?
A plane electromagnetic wave travels in free space along x-axis. At a particular point in space, the electric field along y-axis is 9.3 Vm−1. The magnetic induction (B) along z-axis is:
Which of the following electromagnetic radiations has the smallest wave length?
The velocity of electromagnetic wave is parallel to
Electromagnetic waves are produced by ______.
If `vecE` and `vecB` represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of the electromagnetic wave is along ______.
The source of electromagnetic waves can be a charge ______.
- moving with a constant velocity.
- moving in a circular orbit.
- at rest.
- falling in an electric field.
A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is E = 6 Vm-1 along the y-direction. Its corresponding magnetic field component, B would be ______.
An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative electric permittivity 2.25 from vacuum. The wavelength of this wave in that medium will be ______ × 10-2 cm.
