Physics [1 Mark Question Answer]

A converging lens of suitable focal length is used in the spectacles worn by an old lady for knitting.

The image of the objects at different distances from the eye is brought to focus on the retina by changing the focal length of the eye lens. This is called the power of accommodation of the eye.

1 nm = 10 Å

The white light shall split into its constituent colours and a spectrum shall be formed.

It passes parallel with respect to the base of the prism.

The colour band obtained on a screen on passing white light through a prism is called the spectrum. 

The phenomenon of splitting of white light into its constituent colours is known as dispersion.

Ritter

Hershell

Marconi

Hertz

Newton

Roentgen

Dispersion occurs because light of different colour bend through different angles while passing through a glass prism. 

The colour band obtained on a screen on passing white light through a prism is called the spectrum. 

If a monochromatic light passes through a prism, deviation will occur and not dispersion. 

Principal axis of a lens is the line joining the centres of curvatures of the two surfaces of the lens. 

The SI unit of focal length is 'metre'. 

Focal length of a plane mirror is infinity.

A lens may be defined as a transparent refracting medium bounded by two curved surfaces which are generally spherical. 

A ray of light passing through the optical centre of the lens passes undeviated.

If the medium on both sides of the lens is same, the first and second focal lengths are equal.

Refractive index being the ratio of similar quantities has no units. 

The phenomenon is total internal reflection 

Yes, reflection also takes place with the refraction.

The correct path is that of ray 'B'. 

Ray B is the correct refracted ray because a ray of light travelling from air (rarer medium) to water (denser medium) will bend towards the normal.

Refraction is the bending of light at the surface of separation, which takes when it passes from one optical medium to another optical medium with different optical densities. 

Angle of deviation may be defined as the angle between original path of incident ray and the path of refracted ray. 

No, dispersion is not same as deviation. 

The absolute refractive index of a medium is defined as the ratio of the speed of e-m radiation in free space to the speed of radiation in that medium.

Violet colour of white light has highest refractive index. 

Red colour of white light has least refractive index.