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:
Critical angle for a pair of rarer and denser medium is given by
Given that reflected and refracted rays make an angle of 90o, hence
Angle of reflection + angle of refraction = 90o
According to Snell’s law.
Hence, from eq. (1) and (2), we get
When a ray of light enters a glass slab from air:
How many images of himself does an observer see if two adjacent walls and the ceiling of a rectangular room are mirror surfaced?
A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicated the time 7.10. Then the time on the clock is:
Mirage is a phenomenon due to:
A plane glass slab is kept over various coloured letters; the letter which appears least raised is:
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: