The clear sky appears blue because:
Explanation:
The scattering of light depends on the size of the dust particles and the wavelength of the light. The amount of scattering is inversely proportional to the fourth power of wavelength.
Since, violet and blue lights get scattered more than lights of all other colours by the atmosphere the sky appears blue.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
In Young’s experiment, the ratio of maximum to minimum intensities of the fringe system is 4 : 1. The amplitudes of the coherent sources are in the ratio
|
(a) 4 : 1 |
(b) 3 : 1 |
(c) 2 : 1 |
(d) 1 : 1 |
To obtain a P-type germanium semiconductor, it must be doped with
|
(a) Arsenic |
(b) Antimony |
(c) Indium |
(d) Phosphorus |
A star is moving away from the earth with a velocity of 100 km/s. If the velocity of light is 3 
then the shift of its spectral line of wavelength 5700 Å due to Doppler's effect will be
|
(a) 0.63 Å |
(b) 1.90 Å |
(c) 3.80 Å |
(d) 5.70 Å |
Voltmeters V1 and V2 are connected in series across a D.C. line. V1 reads 80 volts and has a per volt resistance of 200 ohms. V2 has a total resistance of 32 kilo ohms. The line voltage is
|
(a) 120 volts |
(b) 160 volts |
(c) 220 volts |
(d) 240 volts |
If a proton and anti-proton come close to each other and annihilate, how much energy will be released
|
(a) 1.5 |
(b) 3 |
(c) 4.5 |
(d) None of these |
In a photocell bichromatic light of wavelength 2475 Å and 6000 Å are incident on cathode whose work function is 4.8 eV. If a uniform magnetic field of 3 × 10–5 Tesla exists parallel to the plate, the radius of the path describe by the photoelectron will be (mass of electron = 9 × 10–31 kg)
|
(a) 1 cm |
(b) 5 cm |
(c) 10 cm |
(d) 25 cm |
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Fig). When observed from the face AD, the pin shall:
