Nodal Slide Experiment Questions and Answers for Viva

Answer-1: To determine the position of cardinal points of a system of single convex lens and also a combination of two convex lens.

Answer-2: The principal points and nodal points together called cardinal points in an optical system.

Answer-3: Principal Points: The principal points are two hypothetical planes in a lens system at which all the refraction can be considered to happen.
Focal points The point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection.
Nodal points The nodal point of a lens is the point inside a lens where light paths cross before being focused onto a axis of lens.

Answer-4: The nodal slide is an instrument used for locating and measuring the cardinal points of a lens or a system of lenses.

Answer-5: A combination of two or more than two lenses with same principal axis is called the co-axial lens system.

Answer-6: The two conjugate points N1 and N2 on the principal axis for which angular magnification is +1 are called the nodal points (The incident rays of light at the first nodal point emerge after refraction from the second nodal point N2 in a direction parallel to the incident rays.

Answer-7: The part on which the lenses are mounted and which is rotated about the vertical axis .

Answer-8: If the image on the cross slit gets displaced on turning the plane mirror slightly, the image is said to required image .

Answer-9: No, the image on cross slit will not be displayed.

Answer-10: Focal length is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror ? the point where parallel rays of light meet, or converge.

Answer-11: When a lens is defocused, a object point gets rendered as a small circle, called the circle of confusion. (Ignoring diffraction) If the circle of confusion is small enough, the image will look sharp.

Answer-12: The hyper focal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp.

Answer-13: An optical aberration is a departure of the performance of an optical system from the predictions of paraxial optics.

Answer-14: When a beam of light passes through any aperture it spreads out. This effect limits how sharp a lens can possibly be.

Answer-15: A optical test bench with instrumentation which generally includes a collimator, microscope, positioners and a nodal slide used to rotate a lens about its second nodal point. The nodal bench is used to determine the cardinal points of a lens so that measurements of focal length, back focal length, field curvature, distortion, magnification, and blur pattern can be carried out.

Answer-16: When a parallel beam of light is incident on a convergent lens system, its image is formed on a screen (or mirror) placed in its second focal plane. Now if the lens system is rotated about a vertical axis passing through the second nodal point, there is no displacement of the image.