Question
What is meant by pure and impure spectrum?
✓
Answer
Pure spectrum : When rays of white light pass through a prism, each ray forms a spectrum on the screen. If each colour is seen separately in the spectrum, then this type of spectrum is called 'pure spectrum'. The following are the conditions for obtaining a pure spectrum :
(i) The line aperture should be narrow and located at the focus of the converging lens.
(ii) The prism should be in a position of minimum deviation.
(iii) Rays of the same colour emanating from the prism should be focused at one place by the converging lens.
(iv) The incident rays should be parallel.
Impure spectrum : When rays of white light pass through a prism then each ray produces a spectrum on the screen. Due to overlapping of different colors, these colours are not visible separately on the screen. This type of spectrum is called 'impure spectrum'.
(i) The line aperture should be narrow and located at the focus of the converging lens.
(ii) The prism should be in a position of minimum deviation.
(iii) Rays of the same colour emanating from the prism should be focused at one place by the converging lens.
(iv) The incident rays should be parallel.
Impure spectrum : When rays of white light pass through a prism then each ray produces a spectrum on the screen. Due to overlapping of different colors, these colours are not visible separately on the screen. This type of spectrum is called 'impure spectrum'.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A straight wire carrying a current of 12A is bent into a semi-circular arc of radius 2.0cm as shown. What is the magnetic field at O due to:
- Straight segments.
- The semi-circular arc?
A charge of 1.0C is placed at the top of your college building and another equal charge at the top of your house. Take the separation between the two charges to be 2.0km. Find the force exerted by the charges on each other. How many times of your weight is this force?
Find the radius and energy of a $He^+$ ion in the states (a) n = 1, (b) n = 4 and (c) n = 10.
→Distinguish between isotopes and isobars. Give one example for each of the species.
Does focal length of a lens depend on the colour of the light used? Does focal length of a mirror depend on the colour?
Draw the graph to show variation of binding energy per nucleon with mass number of different atomic nuclei. Calculate binding energy/nucleon of $^{40}_{20}\text{Ca}$ nucleus.
Given:
mass of $^{40}_{20}\text{Ca} = 39.962589\text{u}$.
mass of proton $= 1.007825$ u.
mass of neutron $= 1.008665$ u.
and $1\ u = 931\ MeV/C^{2.}$
→Given:
mass of $^{40}_{20}\text{Ca} = 39.962589\text{u}$.
mass of proton $= 1.007825$ u.
mass of neutron $= 1.008665$ u.
and $1\ u = 931\ MeV/C^{2.}$
A long, straight wire of radius r carries a current i and is placed horizontally in a uniform magnetic field B pointing vertically upward. The current is uniformly distributed over its cross-section.
- At what points will the resultant magnetic field have maximum magnitude? What will be the maximum magnitude?
- What will be the minimum magnitude of the resultant magnetic field?
Get the electric field due to on infinitely long straight uniformly changed wire.
An object is to be seen through a simple microscope of focal length 12cm. Where should the object be placed so as to produce maximum angular magnification? The least distance for clear vision is 25cm.
A circular loop of radius a, carrying a current i, is placed in a two-dimensional magnetic field. The centre of the loop coincides with the centre of the field The strength of the magnetic field at the periphery of the loop is B. Find the magnetic force on the wire.
