RRB JE GK Questions 2026

A constructor carries the same name as its class, is called automatically the moment an object is created and is normally used to give the data members their initial values; it returns no value at all, not even void, and it can be overloaded.

Inheritance lets a derived, child or sub class take the members of a base, parent or super class and add its own, which is the main route to code reuse in object-oriented programming; its forms are single, multiple, multilevel, hierarchical and hybrid.

A class only describes the data members and member functions that its objects will have, while an object is created from the class, occupies memory and holds actual values; one class may have any number of objects.

Overloading means defining several functions of the same name in the same class with different numbers or types of parameters, so the compiler decides which one to call; because the decision is taken before the program runs, it is called compile-time or static polymorphism.

James Gosling and his team at Sun Microsystems developed Java, which was first called Oak and was released under the name Java in 1995; its programs are compiled to bytecode and run on the Java Virtual Machine, which makes them platform independent.

Bjarne Stroustrup developed the language at Bell Laboratories, starting it as C with Classes and giving it the name C++ in 1983; it adds classes, inheritance and polymorphism to C while keeping C procedural power, which is why it is called a hybrid language.

Abstraction presents only what the user needs, such as the accelerator and brake of a car, and keeps the internal working out of sight; in C++ it is obtained through abstract classes with pure virtual functions and in Java through interfaces and abstract classes.

Encapsulation means binding the data members and the member functions that act on them inside one unit, the class, and keeping the data private so that it can be reached only through the methods provided; the standard illustration is a capsule holding the medicine inside it.

Recursion is a general programming technique in which a function calls itself, and it works equally well in procedural languages such as C, so it is not a feature of the object-oriented approach.

Simula 67, designed by Ole-Johan Dahl and Kristen Nygaard, introduced the ideas of class, object and inheritance and is therefore treated as the first object-oriented language, from which C++ and Java later borrowed.

Because the rotor carries permanent magnets instead of windings that must be energised, the motor is compact, light and highly efficient over a wide range of speeds, and it gives the strong torque from rest that makes electric cars quick off the mark.

A fuel cell is an electrochemical device, not an engine: hydrogen fed to the anode is split into protons and electrons, the protons cross a membrane, the electrons travel through the external circuit and do work, and at the cathode they recombine with oxygen from the air to form water.

The Battery Waste Management Rules, 2022 were notified under the Environment (Protection) Act and replaced the Batteries (Management and Handling) Rules of 2001.

The BMS is the electronic brain of the pack. It measures the voltage, current and temperature of individual cells or groups of cells, balances their charge so that no cell is overworked, estimates the state of charge and state of health that the dashboard displays, and disconnects the pack when…

The Geological Survey of India reported an inferred lithium resource in the Salal and Haimana area of that district, the first lithium find of real consequence in the country and a significant one because India had been importing virtually all its lithium and its cells.

The second phase shifted the emphasis from private cars to public and shared transport, concentrating its incentives on electric buses, two wheelers, three wheelers and commercial four wheelers, and tying them to conditions on battery type and on the share of parts made in India, while also funding charging stations.

The scheme for Faster Adoption and Manufacturing of Hybrid and Electric Vehicles is a demand and manufacturing support scheme, offering incentives that reduce the purchase price of eligible vehicles and funding charging infrastructure, and it sits with the ministry responsible for the automobile and capital goods industries.

When the driver lifts off or brakes, the electric motor is made to work backwards: the turning wheels drive it, it generates electricity, and that current is fed back into the pack.

LFP cells are prized for safety, long cycle life and the absence of cobalt, which makes them cheaper and less exposed to supply disruption; their weakness is a lower energy density, so a pack of the same range weighs more.

The layered structure of graphite can accept lithium ions between its sheets, a process called intercalation, and release them again without breaking down, which is what makes the cell rechargeable over hundreds of cycles.