Physics: Electricity and Magnetism: UPSC Previous Year Questions (Science and Technology)
2 previous year UPSC Prelims questions on Physics: Electricity and Magnetism (Science and Technology). Choose an option to see the answer and explanation.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 1–2 of 2 questions
UPSC 1999Science and Technology · Physics: Electricity and Magnetism
Q1. Consider the following statements: An ordinary light bulb has a rather short life because the: 1. filament wire is not uniform. 2. bulb cannot be evacuated completely. 3. wires supporting the filament melt at high temperatures. Which of the above statements are correct?
Explanation
Statement 1 is correct: The filament in a light bulb is typically made of tungsten. When the filament is not uniform, the thinner sections tend to heat up more, leading to higher temperatures and stress, which can cause premature failure.
Statement 2 is correct: Light bulbs typically contain an inert gas, like argon, to prevent oxidation of the filament and improve lifespan. Complete evacuation of the bulb is not possible. A small quantity of gases left behind which expands on heating by heat through filament. If the bulb is not evacuated properly, the filament would burn out quickly causing the bulb to have a short life.
Statement 3 is correct: The wires supporting the filament are designed to withstand high temperatures. However if they are not robust enough or if the filament heats up too much, and they can melt, causing the bulb to fail.
UPSC 1999Science and Technology · Physics: Electricity and Magnetism
Q2. Consider the following statements regarding a motor car battery: 1. The voltage is usually 12 V. 2. Electrolyte used is hydrochloric acid. 3. Electrodes are lead and copper. 4. Capacity is expressed in ampere-hour. Which of the above statements are correct?
Explanation
Statement 1 is correct: Most car batteries are 12-volt lead-acid batteries. This is the standard voltage for automotive applications as it provides sufficient power for starting the engine and running electrical systems in vehicles.
Statement 2 is incorrect: The electrolyte used in a car battery is sulfuric acid (H₂SO₄), not hydrochloric acid. Sulfuric acid is mixed with distilled water to create the electrolyte solution, which facilitates the electrochemical reactions in the battery.
Statement 3 is incorrect: The electrodes in a car battery are made of lead (Pb) and lead dioxide (PbO), not copper. The negative electrode (anode) is made of pure lead, and the positive electrode (cathode) is made of lead dioxide.
Statement 4 is correct: The capacity of a car battery is expressed in ampere-hours (Ah). This unit measures the amount of charge a battery can deliver over time. For example, a 50 Ah battery can theoretically deliver 1 ampere of current for 50 hours or 5 amperes for 10 hours.
Answer key for these questions
Q
UPSC year
Correct answer
1
1999
(d) 1, 2 and 3
2
1999
(d) 1 and 4
Frequently asked questions
How many previous year UPSC questions are there on Physics: Electricity and Magnetism?
This page covers 2 previous year UPSC Prelims GS Paper-I questions on Physics: Electricity and Magnetism (Science and Technology), asked from 1996 to 2006. Each has the correct answer and an explanation.
How should I use previous year UPSC questions for Prelims?
Attempt each question first, then open the answer and read the explanation for every option. Repeat by chapter, and track which statements UPSC reuses across years. Previous year questions show the exam pattern and difficulty level.
Which years are covered for Physics: Electricity and Magnetism?
Questions on Physics: Electricity and Magnetism (Science and Technology) are available for 6 years, from 1996 to 2006. Use the Year filter to practise a single paper.
