Railway GK Questions 2026

A transformer raises or lowers an AC voltage using electromagnetic induction between two coils. A transformer has a primary and a secondary coil wound on a common soft-iron core.

Heat, by definition, is energy that flows because of a temperature difference. Thermodynamics recognises two ways in which a system can exchange energy with its surroundings: heat and work.

The plasma membrane is made of lipids and proteins and contains no DNA or RNA. The plasma membrane is the outer boundary of the cell.

Rotational kinetic energy is ½Iω², and the ring has the larger moment of inertia. For a thin ring about the axis through its centre and perpendicular to its plane, all the mass sits at distance R, so I = MR².

A light year is a unit of distance, not of time or brightness. One light year is the distance light travels through a vacuum in one Julian year.

Among the four rocky inner planets, Earth is the largest, with a diameter of about 12,742 km. The inner or terrestrial planets are Mercury, Venus, Earth and Mars, all made of rock and metal.

Using Q = mcΔT, the mass works out to 20,000 ÷ (400 × 10) = 5 kg. The heat needed to warm a body is Q = mcΔT, where m is the mass, c the specific heat capacity and ΔT the rise in temperature.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

Power is the reciprocal of focal length in metres, and a concave lens has a negative focal length. The power of a lens is P = 1/f, with f in metres, and its unit is the dioptre (D).

The formula T₀ = 2π√(L/g) holds only for small swings; at large amplitudes the period grows.

On a level curve, friction alone supplies the centripetal force, so a cyclist slips when the needed force exceeds the maximum friction.

Copper is less reactive than lead, so it cannot push lead out of its compound. In a displacement reaction, a more reactive metal takes the place of a less reactive metal in its salt solution.

Graphite has free electrons that can move through it, so it conducts electricity; diamond and fullerene do not conduct well.

In a short circuit the live and neutral wires touch, the resistance of the path falls almost to zero, and the current shoots up.

A leaf from a sunny day is full of starch made by photosynthesis, and iodine turns starch blue-black. This is the standard school test for starch in a leaf.

A body moving faster than sound outruns its own sound waves, which pile up into a shock wave heard on the ground as a sonic boom.

Xylem carries water along with the minerals dissolved in it from the roots up to the stem and leaves. Plants have two kinds of conducting tissue.

Bacteria have a cell wall and human cells do not, so a drug that attacks the cell wall harms only the bacteria.

Buried organic waste rots without air in a landfill, and bacteria that work without oxygen release methane. Food scraps, paper and garden waste make up a large share of city garbage.

Each nucleotide of DNA is made of these three parts, and many nucleotides joined together form the polynucleotide chain. In a DNA strand, the sugar of one nucleotide is linked to the phosphate of the next by a phosphodiester bond, making a sugar-phosphate backbone.