Physics · Science General

Units and Measurement

1,044 Questions

Master the fundamentals of physics with these practice questions on units and measurement. The topics include fundamental SI units, derived quantities, and specific units for power, force, and light. These questions are essential for building a strong foundation for competitive exams.

SI fundamental unitsUnits of powerDerived quantities unitsThermal energy unitsVolume measurement unitsElectric current units

Units and Measurement Questions

Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

Which of the following pairs of physical quantities have same dimensions?

  1. Force and power

  2. Torque and energy

  3. Torque and power

  4. Force and torque
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Torque is the moment of force given by:$ \vec\tau=\vec r\times \vec F$

It’s unit is Newton-meter.

The unit of work/energy is also Newton-meter or Joule.

Thus, both of these physical quantities have the same units/dimensions.

$[Torque]=[M][L]^{2}[T]^{−2}=[Energy]$
Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

Which of the following statements is incorrect regarding mass. ?

  1. It is a basic property of matter.

  2. The SI unit of mass is kg.

  3. The mass of an atom is expressed in u.

  4. It depends upon the temperature, pressure or location of the object in space.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass is property of mater, which is independent of other properties like temperature, pressure or location of the object in space.

Multiple choice physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

State the S.I. unit. of pressure

  1. Newton

  2. Pascal

  3. Coulomb

  4. Copernicus
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior. The standard unit for pressure is the Pascal, which is a Newton per square meter.

$1Pa=1Nm^{-2}$

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The units of fore and length are made three times of their earlier values. Earlier the energy of a system was $81\ J$. What will be the energy of the same system in new units?

  1. $243$
  2. $729$
  3. $9$
  4. $None\ of\ the\ above$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Energy has dimensions [M L^2 T^-2]. If force [M L T^-2] and length [L] are tripled, then [M L T^-2] -> 3 and [L] -> 3. This implies [M] -> 3 / 3 = 1 and [T^-2] -> 3 / 3 = 1 (no change). Thus, energy scales by [M] * [L]^2 * [T^-2] = 1 * 3^2 * 1 = 9. New energy = 81 * 9 = 729 J.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Units of power and voltage are represented by

  1. W, V

  2. A, V
  3. W, $\Omega$
  4. V, $\Omega$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In our every day lives we use electrical energy to do work for us. This electrical energy is provided either by our power company through the outlets in our wall, or we can buy stored electrical energy in the form of batteries. Different electrical appliances use electrical energy at different rates. Power is the rate at which work is done. The power rating of an appliance tells us the rate at which it uses electrical energy. For example, a 1500 watt hair dryer uses 1500 joules of electrical energy per second.
In any electrical appliance their is a simple relationship between the power output of a component, the potential difference across that component, and the current running through it. This is because charge times potential difference is energy, so (charge per unit time) times (potential difference) gives (energy per unit time).
Thus, we have $P=V I.$
Substituting $V=I R$ from ohm's law, the power relationship can be rewritten as $P={ I }^{ 2 }R$. From this formula, the resistance can be calculated.

hence correct option is A

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

The unit of frequency is:-

  1. Hertz

  2. Joule

  3. Ohm

  4. Kilo Calorie
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Frequency is the number of complete vibrational cycles of a medium per a given amount of time. The frequency would have units of cycles/second, waves/second or vibrations/second. The unit for frequency is the Hertz (abbreviated Hz) where 1 Hz is equivalent to 1 cycle/second. 

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

Hertz stands for:

  1. second
  2. second$^{-1}$

  3. meter
  4. meter$^{1}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hertz is the unit of frequency and frequency is defined as number of vibrations per second ,

        $f=$number of vibrations/ time (in second) ,
which gives frequency in,
$second^{-1}=Hertz$