Q81. Magnetic field lines outside a permanent bar magnet travel from:
Science and Technology: RAS Prelims MCQs
1113 RAS Prelims practice MCQs on science and technology are on this page, in 6 chapters. They cover the basics of everyday science, computers and information technology, defence and space technology in India, genetics, biotechnology and nanotechnology, science and technology policies and government programmes, and recent advances with Indian contributors and indigenisation. Each question has an answer and an explanation.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
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Q82. Which rule is used to determine the direction of the magnetic field produced by a current-carrying straight conductor?
Explanation
Maxwell’s Right-Hand Thumb Rule is used to determine the direction of the circular magnetic field around a straight current-carrying wire. If the thumb of the right hand points in the direction of the conventional current, the curled fingers indicate the direction of the magnetic field lines. This simple rule is fundamental for understanding the relationship between electricity and magnetism in conductors.
Q83. The most suitable material for making the core of an electromagnet is:
Explanation
Soft iron is the most suitable material for the core of an electromagnet because it is easily magnetized and demagnetized. When electric current flows through the surrounding coil, the soft iron becomes a strong magnet. As soon as the current is switched off, it loses almost all its magnetism quickly. This property allows for precise control over the magnetic field in many applications.
Q84. The phenomenon of generating an electric current in a closed circuit by changing the magnetic field is known as:
Explanation
Electromagnetic induction is the process of generating an electromotive force and subsequently an electric current in a closed circuit by changing the magnetic environment. This can be achieved by moving a magnet relative to a coil or by changing the current in a nearby circuit. Discovered by Michael Faraday, this principle is the foundation for the operation of electric generators and transformers.
Q85. An electric motor works on the principle that:
Explanation
An electric motor operates on the principle that a conductor carrying an electric current will experience a mechanical force when placed within an external magnetic field. The interaction between the magnetic field produced by the current and the external field results in a torque that causes the motor’s rotor to spin. This process effectively converts electrical energy into useful mechanical work or motion.
Q86. Match the laws and rules in List I with their corresponding applications or concepts in List II.
| Law/Rule | Application/Concept |
|---|---|
| A. Fleming’s Left-Hand Rule | i. Magnitude of induced EMF |
| B. Fleming’s Right-Hand Rule | ii. Direction of induced current in generators |
| C. Lenz’s Law | iii. Direction of force on a conductor in motors |
| D. Faraday’s Law | iv. Conservation of energy in induction |
Explanation
Fleming’s Left-Hand Rule determines the force direction in motors, while his Right-Hand Rule finds induced current direction in generators. Lenz’s Law relates induction to the conservation of energy, stating that induced effects oppose their cause. Faraday’s Law provides the mathematical framework for calculating the magnitude of induced EMF. Together, these principles explain how magnetic fields and electric currents interact in technology.
Q87. Who discovered the phenomenon of electromagnetic induction?
Explanation
Michael Faraday was a pioneering scientist who discovered the phenomenon of electromagnetic induction in 1831. Through his experiments with moving magnets and coils, he demonstrated that a changing magnetic field could induce an electric current. This discovery revolutionized science and technology, leading to the development of the electric motor, generator, and transformer, which are essential to modern power systems and electronics.
Q88. Materials like iron, nickel, and cobalt that are strongly attracted by magnets are classified as:
Explanation
Materials like iron, nickel, and cobalt are classified as ferromagnetic because they exhibit strong magnetic properties and are highly attracted to magnets. In these substances, atoms have unpaired electrons that align their magnetic moments in small regions called domains. When exposed to an external magnetic field, these domains align, causing the material to become strongly magnetized and sometimes retain permanent magnetism.
Q89. A device that reverses the direction of current in a circuit periodically is called a:
Explanation
A commutator is a rotary electrical switch used in certain types of electric motors and generators. Its primary function is to periodically reverse the direction of current between the external circuit and the rotating coils. This reversal ensures that the magnetic force continues to pull the rotor in the same direction, allowing for continuous rotation rather than just a partial turn or oscillation.
Q90. Which of the following best describes the Earth’s magnetic north pole?
Explanation
The Earth acts like a giant bar magnet, but its magnetic poles are not identical to its geographic ones. The point referred to as the magnetic north pole actually behaves like the south pole of a magnet. This is why the north-seeking end of a compass needle, which is a north pole, is attracted to and points toward the Earth’s northern regions.Answer key for these questions
| Q | Correct answer |
|---|---|
| 81 | (b) North pole to South pole |
| 82 | (a) Maxwell’s Right-Hand Thumb Rule |
| 83 | (c) Soft iron |
| 84 | (d) Electromagnetic induction |
| 85 | (c) Current-carrying conductors in magnetic fields experience force |
| 86 | (a) A-iii, B-ii, C-iv, D-i |
| 87 | (d) Michael Faraday |
| 88 | (a) Ferromagnetic |
| 89 | (c) Commutator |
| 90 | (a) It behaves magnetically like the south pole of a bar magnet. |
Key facts from Science and Technology
- The RPSC paper is General Knowledge and General Science, so science questions come with a strong dose of applied and recent topics.
- Everyday science questions test the laws and terms of physics, chemistry and biology through examples.
- Defence and space questions pair a missile, satellite or mission with its year and organisation.
- Policy questions ask for the year, the body and the aim of schemes like STIP, the National Quantum Mission and BioE3.
- Health, environment and agriculture are on a separate page, with their own chapters.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Science and Technology?
This page has 1113 practice MCQs on Science and Technology. Each has the correct answer, and most have an explanation.
Which chapters does the science and technology set cover?
Six chapters: basics of everyday science; computers, information and communication technology; defence and space technology in India; genetics, biotechnology and nanotechnology; science and technology policies and government programmes; and recent advances, Indian contributors and indigenisation.
Is science and technology part of the RAS Prelims syllabus?
Yes. The RPSC paper is called General Knowledge and General Science, and its syllabus lists science and technology topics along with environment, health, agriculture and government programmes, so questions can come from any of these areas.
How should I prepare science for RAS Prelims?
Revise the concepts by examples, then learn the missions, schemes and scientists with their year and organisation. Attempt each chapter, read the explanations and keep a list of the facts you missed.