High School

13. The time taken by sunlight to travel from the Sun to Earth is:

a) 8.5 minutes
b) 500 minutes
c) 500 seconds
d) 24 hours

14. The dimensional formula of density is:

a) [ML³]
b) LM³
c) [ML⁻³]
d) None

15. Force per unit mass is equivalent to:

a) Acceleration
b) Pressure
c) Density
d) Upthrust

16. One Joule is equal to:

a) 10⁻⁷ erg
b) 10⁻⁷ erg
c) 10⁷ dyne
d) 10⁻⁷ dyne

17. The SI unit for luminous intensity is:

a) Flux
b) Candela
c) Lumen
d) Lux

18. Atmospheric pressure is measured by:

a) Sphygmomanometer
b) Barometer
c) Pressure gauge
d) Hydrometer

19. A "shake" is a unit of:

a) Distance
b) Velocity
c) Time
d) Density

Answer :

  1. The time taken by sunlight to travel from the Sun to Earth is approximately 8.5 minutes. The correct answer is option (a) 8.5 minutes. This time is based on the average distance from the Earth to the Sun, which is about 93 million miles or 150 million kilometers. Light travels at about 299,792 kilometers per second, and it takes approximately 499 seconds for light to make this journey, which translates to roughly 8.3 minutes.

  2. The dimensional formula of density is [ML^{-3}]. The correct answer is option (c) [ML^{-3}]. Density is defined as mass per unit volume. In dimensional analysis, mass (M) is multiplied by volume (L^3) raised to the power of -1 as it is in the denominator.

  3. Force per unit mass is equivalent to acceleration. The correct answer is option (a) Acceleration. By Newton's second law, Force = Mass × Acceleration, which means that Acceleration = Force per Unit Mass.

  4. One Joule is equal to 10^7 erg. The correct answer is option (c) 10^7 erg. In the CGS system, 1 Joule is defined as 10^7 ergs because 1 erg = 10^{-7} Joule.

  5. The SI unit for luminous intensity is candela. The correct answer is option (b) Candela. The candela is a basic unit of luminous intensity in the International System of Units (SI).

  6. Atmospheric pressure is measured by a barometer. The correct answer is option (b) Barometer. A barometer is an instrument used to measure atmospheric pressure, which is important for weather forecasting and determining altitude.

  7. Shake is a unit of time. The correct answer is option (c) Time. A shake is equal to 10^-8 seconds and is often used in nuclear physics to measure short time intervals.