Tag: need of unit for measurement

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Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

Which of the following does not has fundamental unit?

  1. Mass

  2. Time

  3. Force

  4. length
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The fundamental units are the units of the fundamental quantities, as defined by the International System of Units. They are not dependent upon any other units, and all other units are derived from them. There are seven basic fundamental quantities: Length, mass, time, electric current, amount of substance, luminous intensity & temperature. The quantities which are derived with the help of these basic physical quantities are called derived quantities. They are density, volume, pressure, force, etc.

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

The wavelength of light is usually expressed in

  1. Micron

  2. Fermi

  3. Nanometer

  4. Angstrom
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Angstrom $(\dot A)$ unit of length used chiefly in measuring wavelengths of light, equal to $10^{-10}$ metre, or $0.1$ nanometer.  It is used to express wavelengths of visible light, ultraviolet (UV) light, X rays, and gamma rays.

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

In a tug-of-war between the teams A and B, the rope breaks at a point which is nearer to A. Then

  1. A has applied more force

  2. B has applied more force

  3. A and B both have applied same force

  4. Neither has applied any force
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a tug-of-war, the tension throughout the rope is uniform. If the rope breaks, it is due to a structural weakness at that point, not because one side pulled harder than the other.

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

The gravitational unit of force in the metric system is

  1. g wt

  2. N

  3. kg wt

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gravitational force is the force exerted by earth on any body which attracts to body towards earth. It is same as any other force.  The gravitational unit of force in the metric system is $kg\,wt$.

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

The amount of energy emitted per unit time is called _______ .

  1. Solar luminosity

  2. Luminous intensity

  3. Luminous flux

  4. Solar intensity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Solar luminosity is defined as the total amount of energy emitted by a star per unit time. Luminous flux and intensity relate to human perception of light, not total energy emission.

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

The unit of power is

  1. Joule per second only

  2. Joule only

  3. Joule per second and watt both

  4. Watt only

  5. Erg
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Power is defined as work divided by time, so its units are joules/second. Scientists have another name for this unit, too. It's the watt, named after James Watt, the Scottish inventor who helped develop the steam engine that powered the Industrial Revolution. In the SI system, the watt is defined as:


$1\,watt=1\,J/s=1\,kg\,m^2/s^3$

Multiple choice standardized measurement measurement of physical quantities need of unit for measurement measurements and experimentation physics

The correct relation is -

  1. Density = Mass $ \displaystyle \times $ Volume
  2. Mass = Density $ \displaystyle \times $ Volume
  3. Volume = Density $ \displaystyle \times $ Mass
  4. Density = Volume $ \displaystyle \div $ Mass
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

We know that Density = Mass / Volume

So, Mass = Density X Volume (Option B)