Advertisements
Advertisements
प्रश्न
Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
उत्तर
Microwaves are suitable for the radar system used in aircraft navigation. Range of frequency of microwaves is 108 Hz to 1011 Hz.
APPEARS IN
संबंधित प्रश्न
Use the formula λm T= 0.29 cm K to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?
Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 cm (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 MHz (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).
(c) 2.7 K [temperature associated with the isotropic radiation filling all space-thought to be a relic of the ‘big-bang’ origin of the universe].
(d) 5890 Å - 5896 Å [double lines of sodium]
(e) 14.4 keV [energy of a particular transition in 57Fe nucleus associated with a famous high resolution spectroscopic method (Mössbauer spectroscopy)].
When a Coolidge tube is operated for some time it becomes hot. Where does the heat come from?
If the potential difference applied to the tube is doubled and the separation between the filament and the target is also doubled, the cutoff wavelength
If the current in the circuit for heating the filament is increased, the cutoff wavelength
The distance between the cathode (filament) and the target in an X-ray tube is 1.5 m. If the cutoff wavelength is 30 pm, find the electric field between the cathode and the target.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Name the scientist who discovered Ultraviolet rays
Choose the correct option.
The EM wave emitted by the Sun and responsible for heating the Earth’s atmosphere due to greenhouse effect is
An e.m. wave exerts pressure on the surface on which it is incident. Justify.
For television broadcasting, the frequency employed is normally
