The figure shows variation of photocurrent with anode potential for a photo- sensitive surface for three different radiations. Let Ia , lb and Ic be the intensities and va , vb and vc , be the frequencies for the curves a, b and c respectively. Then
va = vb and Ia ≠ Ib
va = vc and Ia = Ic
va = vb and Ia = Ib
vb = vc and Ib = Ic
In a pond of water, a flame is held 2 m above the surface of water. A fish is at depth of 4 m from water surface.Refractive index of warer i . The apparent height of the lame from the eyes of fish is
5.5 m
6 m
White light is incident on the interface of glass and air, as shown in the figure. If green light is just totally and internally reflected then the emerging ray in air contains
all colours
yellow, orange and red
violet, indigo and blue
all colours except green
A convex lens made up of a material of refractive index µ1 is immersed in a medium of refractive index µ2 as shown in the figure. The relation between µ1 and µ2 is
µ1 < µ2
µ1 > µ2
µ1 = µ2
If a flint lens glass of dispersive power 0.066 renders achromatic to a convex lens of crown glass of focal length 60 cm and dispersive power 0.033, then its focal length is
− 60 cm
+ 60 cm
− 120 cm
+ 120 cm
C.
− 120 cm
Two coherent light beams of intensity I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are
5 I and I
5 I and 3 I
9 I and I
9 I and 3 I
If Young's double slit experiment is performed in water instead of air, then
no fringes would be seen
fringe width would decrease
fringe width would increase
fringe width would remain unchanged
In Young's double-slit experiment, the angular width of fringe formed on a distance screen is 0.1°. If wavelength of light is 6000 , then spacing between the slits is
3.4 × 10-4 m
4.3 × 10-4 m
5.4 × 10-4 m
6.3 × 10-4 m
A person uses spectacles of power + 2 D. He is suffering from
myopia
presbyopia
astigmatism
hypermetropia