Free Physical Quantities and Units MCQs with Answers

11. Five energies are listed.5 KJ5mJ 5MJ 5nJStarting with the smallest first, what is the order of increasing magnitude of these energies?

• A. 5nJ -> 5 mJ -> 5 kJ -> 5 MJ
• B. 5 nJ -> 5 kJ -> 5 MJ -> 5 mJ
• C. 5 kJ -> 5 mJ -> 5 MJ -> 5 nJ
• D. 5 mJ -> 5 nJ -> 5 kJ -> 5 MJ

Explanation: In order to solve this you must know the value and symbol of the number prefix. (Refer to the table below)5 kJ = 5 x10^3J5 mJ = 5 x10^-3 J5 MJ = 5 x10^6 J5 nJ = 5 x10^-9 JThe order of increasing magnitude will be 5 x10^-9 J < 5 x10^-3 J < 5 x10^3J < 5 x 10^6 J5 nJ < 5 mJ < 5 kJ < 5 MJ

12. Michelson measured the length of standard metre in terms of the wavelength of:

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

Explanation: Michelson measured the length of the standard meter using the interference fringes produced by red cadmium light. He used a device called an interferometer to measure the wavelength of the light and used it to determine the length of the standard meter.The interferometer creates interference patterns by splitting a beam of light into two paths, allowing them to recombine and create an interference pattern. By measuring the fringe pattern and knowing the wavelength of the light source, the length of the standard meter can be determined.

13. 1 joule is equal to:

• A. 104 ergs
• B. 105 ergs
• C. 106 ergs
• D. 107 ergs

Explanation: One Joule is the amount of work done when a force of 1 newton displaces a mass through a distance of 1 meter in the direction of the force applied. One joule = Nm (SI ) One joule = 107 ergs (CGS) Hence, D is the correct option

14. 1 light year distance is:

• A. Distance travelled by earth in one year
• B. Distance travelled by star in one year
• C. Distance travelled by light in one year
• D. Distance travelled by light in one galactic year

Explanation: The following is the solution:Option C is correct since it gives the right definition of one light year.Option A is incorrect since it gives simply the distance of earth in orbit.Option B is incorrect since it gives simply the distance travelled by the star in space.Option D is incorrect since one galactic year is equal to 230 million light-years. The galactic year, also known as a cosmic year, is the duration of time required for the Sun to orbit once around the centre of the Milky Way Galaxy.

15. All of the following are equivalent to watt except:

• A. (Amperes)2ohm
• B. Joules/ sec
• C. Amperes x volts
• D. Amperes/volt

Explanation: Power is measured in watts. P = I x V (power is current times voltage) and it is NOT current divided by voltage. So, A/V can't be equivalent to watt and hence, option D is correct.