Free Physics in Daily Life MCQs with Answers

151. Heat of sun reaches the earth by ___________?

• A. Convection
• B. radiation
• C. Conduction
• D. None of these

Explanation: The Sun-to-Earth distance is essentially a vacuum, so neither conduction nor convection can carry the heat across it. Solar energy reaches Earth by electromagnetic radiation.

152. For seeing objects at the surface of water from a submarine under water, the instrument used is ________?

• A. Periscope
• B. Telescope
• C. Kaleidoscope
• D. Spectroscope

Explanation: A periscope uses mirrors or prisms to let someone view objects above the water while remaining submerged. Telescopes magnify distant objects, whereas kaleidoscopes and spectroscopes serve different purposes.

153. Escape velocity of a rocket fired from the earth towards the moon is a velocity to get rid of the _______?

• A. Centripetal force due to the earth's rotation
• B. Earth's gravitational pull
• C. Pressure of the atmosphere
• D. Moon's gravitational pull

Explanation: Escape velocity is the minimum speed needed to escape a body's gravitational field without further propulsion. For a rocket leaving Earth toward the Moon, the relevant pull initially is Earth's gravity, not atmospheric pressure or the Moon's weaker pull.

154. Friction can be reduced by changing from _________?

• A. Rolling to sliding
• B. Sliding to rolling
• C. Dynamic to static
• D. Potential energy to kinetic energy

Explanation: Rolling friction is much smaller than sliding friction because the surfaces do not continually scrape past each other. This is why wheels, rollers and ball bearings make movement easier.

155. "Father of Optics" is the title given to__________?

• A. Ibn-al-Haitham
• B. Ibn-e-Sina
• C. Al-Kandi
• D. Al-Biruni

Explanation: Ibn al-Haytham, known in the Latin West as Alhazen, is called the Father of Optics because he systematically studied vision, light and reflection. Ibn Sina and Al-Biruni are associated mainly with medicine and broader natural sciences, respectively.

156. The light rays used for eliminating bacteria?

• A. X-rays
• B. infrared rays
• C. microwave radiation
• D. ultra-violet radiation

Explanation: Ultraviolet radiation damages the DNA of microorganisms and is therefore used to disinfect water, air and surfaces. X-rays can also kill cells at high doses, but UV is the standard radiation used for routine germicidal treatment.

157. The Earth behaves like a magnet with ______ poles?

• A. Four
• B. Three
• C. Two
• D. None of these

Explanation: Earth’s magnetic field has two main magnetic poles, approximately near the geographic North and South Poles. These are magnetic poles, not four geographic or magnetic divisions.

158. The Quantity of matter present in an object is its ________?

• A. Density
• B. Weight
• C. Mass
• D. None of these

Explanation: Mass measures the quantity of matter in an object and remains essentially the same wherever the object is located. Weight is the gravitational force on that mass, while density is mass per unit volume.

159. Unit of force in (SI) is __________?

• A. Meter
• B. Newton
• C. Kilogram
• D. None of these

Explanation: The newton is the SI unit of force, equal to the force needed to give a 1-kilogram mass an acceleration of 1 metre per second squared. The metre measures length and the kilogram measures mass.

160. Persistance of vision is the principle behind?

• A. Camera
• B. Spectroscope
• C. Cinema
• D. Periscope

Explanation: Cinema depends on persistence of vision, in which the eye briefly retains an image so rapidly projected frames appear as continuous motion. A camera records images but does not rely on this visual illusion for its basic operation.