Free Physics in Daily Life MCQs with Answers

141. The frequency of a turning fork determined by a:

• A. Magnetic tape
• B. Modulator
• C. Sonometer
• D. Reed instrument

Explanation: A sonometer determines the frequency of a tuning fork by comparing its vibration with the vibration of a stretched string. The other devices are not used for this measurement.

142. A definite area or a space where some thermodynamic process takes place is known as?

• A. Thermodynamic system
• B. Thermodynamic cycle
• C. Thermodynamic process
• D. Thermodynamic law

Explanation: A thermodynamic system is the defined region or quantity of matter selected for study. A process describes a change in the system, while a cycle is a sequence returning it to its initial state.

143. A moving object always possesses?

• A. Potential Energy
• B. Kinetic Energy
• C. Thermal energy
• D. Magnetic energy

Explanation: Motion gives an object kinetic energy, calculated as one-half its mass multiplied by the square of its speed. Potential energy may also be present, but it is not guaranteed merely by motion.

144. What do we call when the sound of frequency will be below 20 Hz?

• A. Audio sounds
• B. Infrasonic
• C. Ultrasonic
• D. Supersonics

Explanation: Sound below 20 hertz is called infrasonic sound and is generally below the lower limit of human hearing. Ultrasonic sound is the opposite category, with frequencies above 20,000 hertz.

145. Which colour of light is deviated least ________.

• A. Red
• B. Blue
• C. Violet
• D. Green

Explanation: Red light is deviated least in a prism because it has the longest wavelength and the lowest refractive index among the listed visible colours. Violet, with the shortest wavelength, deviates most.

146. The S. I. unit of refractive index is _______?

• A. meter
• B. cm
• C. watt
• D. no unit

Explanation: Refractive index is a ratio of the speed of light in vacuum to its speed in a medium, so the units cancel. It is therefore dimensionless and has no SI unit.

147. During which process of energy exchange does cold air displace warmer air?

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

Explanation: Cold air is denser, so it sinks and displaces warmer, less-dense air, producing convection currents. Radiation and conduction do not involve bulk movement of air.

148. In general, good absorbents of electromagnetic radiation are also good___________?

• A. Radiators
• B. Conductors
• C. Insulators
• D. Semi Conductors

Explanation: A good absorber of radiation is generally also a good emitter, or radiator, of radiation. This is the basis of Kirchhoff’s law of thermal radiation.

149. What method of energy transfer requires no medium for transfer?

• A. Radiation
• B. Convection
• C. Conduction
• D. A and B both

Explanation: Radiation transfers energy through electromagnetic waves and can travel through a vacuum, so it requires no material medium. Conduction and convection require matter.

150. During which process does heat transfer occur because of density differences__________?

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

Explanation: Convection transfers heat through the movement of fluids caused by density differences: warmer, less-dense fluid rises while cooler, denser fluid sinks. Conduction does not involve bulk fluid motion.