The frequency of y-rays, X-rays and ultraviolet rays are a, b and c respectively. Then
A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of
both (a) and (b)
In a certain region of space electric file and magnetic field are perpendicular to each other and an electron enters in region perpendicular to the direction of and both and moves undeflected, then velocity of electron is
Two sodium lamps are used in an interference experiment. The intensity produced by both lamps individually on the screen is I. The ratio of intensity of maxima to intensity of minima on the screen is
∞:1
λa and λm are the wavelengths of a beam of light in air and in a medium respectively. If θ is the polarising angle, the correct relation between λa , λm and θ is
λa = λm tan2 θ
λm = λa tan2 θ
λm = λa cot θ
A TV tower has a height of 100 m. How much population is covered by the TV broadcast if the average population density around the tower is 1000 km-2 (radius of earth = 6370 km)?
4 lakh
40,000
4000
40 lakh
Which of the following has minimum wavelength?
X-rays
Ultraviolet rays
y-rays
Cosmic rays
The Young's double slit experiment is performed with blue and with green light of wavelengths 4360 Å and 5460 Å respectively. If x is the distance of the 4th maxima from the central one, then
x(blue) = x(green)
x(blue) > x(green)
x(blue) < x(green)
x(blue) / x(green) = 5460/4360
Which of the following is the longest wave?
Ozone layer blocks the radiations of wave length
less than 3 × 10-7 m
equal to 3 × 10-7 m
more than 3 × 10-7 m
all of the above
