The correct answer is Statement (a) is correct and (b) its correct explanation. Explanation & Key Takeaways: • Refraction of Light: • When a ray of light propagating in a medium enters the other medium (transparent mediums), it deviates from its path. (Statement 1 is correct) • This phenomenon of change in the direction of propagation of light at the boundary, when it passes from one medium to another medium, is called the refraction of light. • When a ray of light enters from rarer medium to denser medium from (air to water) it deviates towards the normal drawn on the boundary of two media at the incident point. • The entity that doesn't change is the frequency. • The entity that changes are wavelength and velocity. (Statement 2 is correct) • The refractive index is also equal to the velocity of light c of a given and the wavelength in empty space divided by its velocity v in a substance. • Thus, Velocity, Wavelength & Refractive index changes when light travels from one medium to another but Frequency remains unchanged. • Similarly, in passing from denser to rarer medium, a ray deviates away from the normal. • If the light is incident normally on the boundary, i.e. parallel to normal, it enters the second medium undeviated. • Therefore we can infer that due to the difference in the velocity light changes its direction while passing from one medium to another medium. Related Concepts: • Wavelength: • It is the distance between any two nearest particles of the medium, vibrating in the same phase. • It is denoted by the Greek letter lambda. • SI unit: Angstrom. • Frequency: • It is defined as the number of vibrations completed by the particle in one second. • SI unit: Hertz