## December 16, 2013

### Senior Inter Physics - Ray Optics Imp Questions VSA Questions - New Syllabus

Senior Inter: Ray Optics: Reflection, Refraction and Total internal reflection

Q: Define focal length and radius of curvature of a concave lens?
A: The distance of focal point from optic centre is known as focal length (f).
The distance between centre of lens and centre of curvature is called radius of curvature (R).

Q: What is optical density and how it differ from mass density?
A: Optical density is the property of a medium to slow down the speed of light. A medium of high refractive index has more optical density.
Mass per unit volume of a substance is m
called mass density (d = m/v ). An optically v denser medium may have less mass density.

Q: Define 'power' of a convex lens. What is its unit?
A: The tangent of angle by which a convex lens converges a beam of light, of unit breadth at its optic centre to its focus is called power of a convex lens. P = 1/f

Q: What is dispersion? which colour gets relatively more dispersed?
A: The phenomenon of splitting of light into its component colours is known as dispersion. Dispersion of white light gives VIBGYOR colours. The colour
with less wavelength disperses more. Thus violet colour undergoes more deviation.

Q: What is myopia? How can it be corrected?
A: It is one of optical defect of human eye. In which light ∝ rays are coming from distant object are converged at a point infront of retina. This defect is called shortsightedness. This can be corrected by using a concave lens.

Q: What is hypermetropia? How it can be corrected?
A: This is one of eye defect. In this incoming light from object is converged at a point behind the retina. This is called farsightedness. This defect can be corrected by using a convex lens.