Science chapter practice
Practise 80+ Physics in Everyday Life MCQs for UPSC Prelims in Science, including 40+ previous year questions. The sample set below is shown with correct answers and explanations.
12 sample questions are shown here; sign up free to practise all 80.
Which one of the following is the context in which the term 'qubit' is mentioned?
Explanation
Correct. A qubit (quantum bit) is the basic unit of information in quantum computing, analogous to a classical bit but capable of existing in superposition states.
In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following? 1. Area of the hole in the lid 2. Temperature of the flame 3. Weight of the lid Select the correct answer using the code given below.
Explanation
Correct. The cooking temperature inside a pressure cooker depends on the internal steam pressure, which is governed by the area of the vent hole (through which steam escapes) and the weight of the lid/whistle (which determines the pressure needed to release steam).
With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps have longer life span than LED lamps. 3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. Select the correct answer using the code given below.
Explanation
Correct. Sodium lamps emit omnidirectional (360°) light requiring reflectors, while LEDs are directional. Sodium lamps produce near-monochromatic yellow light, whereas LEDs can produce a wide colour spectrum. Statement 2 is false because LEDs outlast sodium lamps.
Organic Light Emitting Diodes (OLEDs) are used to create digital display in many devices. What are the advantages of OLED displays over Liquid Crystal displays? 1. OLED displays can be fabricated on flexible plastic substrates. 2. Roll-up displays embedded in clothing can be made using OLEDs. 3. Transparent displays are possible using OLEDs. Select the correct answer using the code given below.
Explanation
Correct. OLEDs are organic compounds that emit light when current passes through them. They can be deposited on flexible plastic substrates (1), enabling roll-up wearable displays (2), and since they do not need a backlight, transparent displays are feasible (3).
Ball bearings are used in bicycles, cars, etc., because:
Explanation
Correct. Ball bearings convert sliding friction into rolling friction by reducing the effective area of contact between the wheel and the axle, thereby minimising energy loss.
Consider the following phenomena: 1. Size of the sun at dusk 2. Colour of the sun at dawn 3. Moon being visible at dawn 4. Twinkle of stars in the sky 5. Polestar being visible in the sky Which of the above are optical illusions?
Explanation
Correct. The sun appears larger at dusk due to the 'moon illusion' effect near the horizon, its reddish colour at dawn is caused by atmospheric scattering (Rayleigh scattering), and the twinkling of stars is caused by atmospheric refraction — all are optical illusions.
Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this? 1. Dispersion 2. Refraction 3. Internal reflection Select the correct answer using the codes given below.
Explanation
Correct. A rainbow forms because sunlight entering a raindrop is refracted, dispersed into its component colours, and then internally reflected before exiting the drop and reaching the observer.
The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?
Explanation
Correct. Water has maximum density at 4°C. As surface water cools below 4°C it becomes lighter and stays on top, eventually freezing, while the denser 4°C water sinks and remains liquid at the bottom.
What is the principle by which a cooling system (radiator) in a motor car works?
Explanation
Correct. A car radiator works primarily on the principle of convection — hot coolant circulates from the engine to the radiator where moving air carries away heat through convective heat transfer.
Which one of the following types of waves are used in a night vision apparatus?
Explanation
Correct. Night vision devices detect infrared radiation emitted by warm objects and convert it into a visible image, allowing vision in complete darkness.
Assertion (A): Radio waves bend in a magnetic field. Reason (R): Radio waves are electromagnetic in nature.
Explanation
Correct. Radio waves, being electromagnetic waves, do not carry electric charge and therefore are not deflected by a magnetic field. However, the reason is true — radio waves are indeed electromagnetic in nature.
Which one of the following laser types is used in a laser printer?
Explanation
Correct. Laser printers use compact, low-power semiconductor (diode) lasers to scan and create an electrostatic image on the photosensitive drum.
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