RRB JE GK Questions 2026

White light is a mixture of colours, and the refractive index of the glass of a prism is slightly different for each of them, being greatest for violet and least for red.

In myopia the eyeball is too long or the lens of the eye too strongly converging, so rays from a distant object meet in front of the retina and the person cannot see far objects clearly.

An optical fibre is a thin thread of glass or plastic with a core of higher refractive index surrounded by a cladding of lower refractive index.

On a hot day the air touching the road is heated and becomes rarer than the cooler air above it.

The power of a lens is the reciprocal of its focal length expressed in metres, that is P equals 1 divided by f. Fifty centimetres is 0.5 metre, and the reciprocal of 0.5 is 2, so the power is two dioptres.

A convex mirror curves outward and spreads the light that falls on it, so it always forms a virtual, erect and diminished image, whatever the distance of the object.

Rays reflected from a plane mirror diverge and only appear to come from a point behind the mirror, so the image cannot be caught on a screen and is virtual.

Newton passed a narrow beam of sunlight through a glass prism in a darkened room and obtained a band of seven colours on the wall, which he named the spectrum.

By the sign convention the focal length of a concave lens is negative, so f is minus 15 centimetres, and the object distance measured against the direction of the incident light is minus 30 centimetres.

A denser medium has a higher refractive index, and the refractive index is the speed of light in vacuum divided by its speed in the medium, so light must travel more slowly inside it.

Virtualization creates a software layer over the physical processor, memory and storage of a machine, so that one server can be divided into several virtual machines, each running its own operating system as though it had hardware of its own.

Distillation separates a liquid from a solution or from another liquid by boiling it and condensing the vapour, so it is used when the components differ in boiling point, as in getting pure water from salt water or separating acetone from water.

Among the allotropes of carbon, graphite has the lowest standard enthalpy of formation, which is taken as zero, so it is the reference state and the most stable form under ordinary conditions of temperature and pressure.

The American computer scientist John McCarthy is called the father of artificial intelligence because he coined the term itself in his proposal for the Dartmouth summer research project of 1956, the meeting at which the field was born.

A daisy wheel printer prints by striking the paper, so it is an impact printer. It carries a flat wheel with spokes, each spoke ending in a moulded letter or figure, and the wheel looks like the petals of a daisy, which gives it its name.

Bias in an artificial intelligence system is traced to three sources, the data it learns from, the algorithm that learns, and the people who build and use it; ability is not one of them, because the skill of a model is a measure of how well it performs, not a…

The hexadecimal system has base sixteen, so it needs sixteen symbols for a single place.

Cache is a small, very fast memory that sits between the processor and the main memory and holds the instructions and data the processor has used most recently.

The Post Office Protocol, best known in its third version POP3, lets a mail client download messages from a mail server, and it works in two modes.

The Specific Absorption Rate measures how much radio energy from a handset the body takes in, in watts per kilogram of tissue.