Free Physics in Daily Life MCQs with Answers

221. Why the colour of the Ocean appears blue?

• A. Because the sunlight falling on it is scattered.
• B. Because the sunlight falling on it is absorbed.
• C. Because the sunlight falling on it is refracted.
• D. Because the sunlight falling on it is reflected.Chemistry

Explanation: Water absorbs much of the red part of sunlight, while blue light is scattered back toward the observer more effectively, making deep ocean water appear blue. Reflection contributes to surface appearance but is not the main explanation here.

222. The distance between the optical centre of a convex lens and its principal focus is called its_______?

• A. Focal Length
• B. Radius of Curvature
• C. Power
• D. Magnification

Explanation: The focal length is the distance from the optical centre of a lens to its principal focus. Radius of curvature refers to the curvature of a lens surface, not this centre-to-focus distance.

223. A convex mirror always ___________ ?

• A. Forms a real image
• B. Forms a virtual image
• C. Forms an inverted image
• D. Produces a larger image

Explanation: A convex mirror always produces a virtual, upright, and diminished image because reflected rays diverge and only appear to come from behind the mirror. It therefore does not form a real or enlarged image for an ordinary object.

224. Which of the following is a force?

• A. Heat
• B. Light
• C. Magnetism
• D. Kinetic

Explanation: Magnetism produces forces of attraction and repulsion, so it is treated as a force-producing physical interaction. Heat and light are forms of energy, while kinetic energy is energy due to motion.

225. Dioptre is a unit of measurement for __________ ?

• A. Current
• B. Lens
• C. Force
• D. Focal Length

Explanation: A dioptre is the unit of optical power of a lens, equal to the reciprocal of its focal length in metres. Thus a lens with a focal length of 0.5 metre has a power of 2 dioptres.

226. Eletromagneticism is the branch of___________?

• A. Chemistry
• B. Physics
• C. Both
• D. None of these

Explanation: Electromagnetism is a branch of physics that studies electric charges, electric fields, magnetic fields, and their interaction. Chemistry may use these principles but is not the branch that defines them.

227. Sound travels in air at an average speed of nearly________ ?

• A. 1257 miles per hour
• B. 755 miles per hour
• C. 330 miles per hour
• D. None of these

Explanation: Sound travels through air at about 343 metres per second, which is roughly 767 miles per hour under ordinary conditions. Therefore 755 miles per hour is the closest option.

228. When sound waves travel from air to water which of the following quantities remains unchanged?

• A. Speed
• B. Frequency
• C. Intensity
• D. Wavelength

Explanation: The frequency of a wave is fixed by its source and does not change when sound enters another medium. Its speed and wavelength change according to the new medium, and intensity may also change.

229. Which instrument is used to measure the power of electric circuit ?

• A. Wavemeter
• B. Viscometer
• C. Wattmeter
• D. None of these

Explanation: A wattmeter measures electrical power directly in watts by combining measurements of voltage and current. A wavemeter measures wavelength, while a viscometer measures fluid viscosity.

230. Tyndall effect is related to the ______ of light?

• A. Reflection
• B. Dispersion
• C. Scattering
• D. Refraction

Explanation: The Tyndall effect is the visible scattering of light by colloidal particles, as seen when a beam passes through dusty air or mist. Reflection, refraction and dispersion are different optical effects.