A ray of light passes from vacuum into a medium of refractive index, the angle of incidence is found to be twice the angle of refractlon. Then the angle of incidence is
If α and β are the current gain in the CB and CE configurations respectively of the transistor circuit, then
infinite
1
2
0.5
The apparent frequency of the whistle of an engine changes in the ratio 9 : 8 as the engine passes a stationary observer. If the velocity of the sound is 340 ms-1, then the velocity of the engine is
40 ms-1
20 ms-1
340 ms-1
180 ms-1
The width of a single slit if the first minimum is observed at an angle 2° with a light of wavelength 6980
0.2 mm
2 × 10-5 mm
2 × 105 mm
2 mm
A silicon specimen is made into a p-type semiconductor by doping, on an average, one indium atom per 5 x 107 silicon atoms. If the number density of atoms in the silicon specimen is 5 x 1028 atom/m3, then the number of acceptor atoms in silicon per cubic centimetre will be
2.5 × 1030 atom/cm3
2.5 × 1035 atom/cm3
1 × 1013 atom/cm3
1 × 1015 atom/cm3
In a photoelectric effect measurement, the stopping potential for a given metal is found to be V volt when radiation ofwavelength λ0 is used. If radiation of wavelength 2λ0 is used with the same metal then the stopping potential (in volt) will be
2V0
In artificial radioactivity, 1.414 x 106 nuclei are disintegrated into 106 nuclei in 10 min. The half-life in minutes must be
5
20
15
30
A.
5
From Rutherford-Soddy law
If ε0 and µ0 are the electric permittivity and magnetic permeability of free space and ε and µ are the corresponding quantities in the medium, the index of refraction of the medium in terms of above parameter is
A light ray of 5895 wavelength travelling in vacuum enters a medium of refractive index 1.5. The speed of light m the medium is
3 × 108 m/s
2 × 108 m/s
1.5 × 108 m/s
6 × 108 m/s
The half-life of radon is 3.8 days. How many radon will be left out of 1024 mg after 38 days
1 mg
2 mg
3 mg
4 mg