are the electric permittivity and the magnetic permeability in a free space, ε and μ are the corresponding quantities in the medium, the index of refraction of the medium is:


Correct option is


The velocity of electromagnetic waves in vacuum.


The velocity of electromagnetic waves in medium.




A plane glass slab is kept over various coloured letters; the letter which appears least raised is:


A ray of light from a denser medium strikes a rarer medium at an angle of incidence i. If the angle of reflection is r and the angle of refraction is r’and reflected and refracted rays make an angle of 90o with each other, then the critical angle will be: 


The wavelength of light diminishes μ times in the medium. A diver from inside water (μ = 1.33) looks at an object whose natural colour is green. He sees the object as: 


Air has refraction index of 1.0003. The thickness of air column, which will have one more wavelength of yellow light (6000 Å) than in the same thickness of vacuum is: 


A ray of light travelling inside a rectangular glass block of refractive index  is incident on the glass-air interface at an angle of incidence of 45o. The refractive index of air is one. Under these conditions the ray:


The critical angle of for light going from medium x into medium y is θ. The speed of light in medium x is v. The speed of light in medium y is:     


Monochromatic light of wavelength  travelling in a medium of refractive index n1 enters a denser medium of refractive index n2. The wavelength in the second medium is:    


When seen in green, the saffron and green portions of our national flag will appear to be: 


Light travels through a glass plate of thickness t and having refractive indexμ. If c be the velocity of light in vacuum, the time taken by the light to travel this thickness of glass is:


A perfectly reflecting mirror has an area of 1 cm2. Light energy is allowed to fall on it for one hour at the rate of 10 W/cm2. The force that acts on the mirror is: