Measurement MCQs for NEET — Physics Questions with Answers

$ 1 amu = 1.66 \times 10 ^ {-27 } kg $ $ = 1.66 \times 10 ^ {-24} gm $ $ 1 gm = 6.023 \times 10 ^ {23} amu $

Power is defined as the rate at which work is done or energy is transferred. The units of power are watt (W), which is equivalent to joule/second (J/s). Other valid units of power include $( ext{ampere})^2 imes ext{ohm}$ and $ ext{ampere} imes ext{volt}$. However, ampere/volt does not represent a unit of power.

Angular acceleration in the SI system is measured in radians per second squared ($ ext{rad}/( ext{sec})^2$). This unit expresses how quickly the angular velocity of an object is changing with time.

The universal gravitational constant (G) is defined in Newton's law of gravitation, which states that the force (F) between two masses (m1 and m2) is proportional to the product of their masses and inversely proportional to the square of the distance (r) between them. Mathematically, it is given by: $$ F = G rac{m1 imes m2}{r^2} $$. Rearranging this equation to solve for G, we get: $$ G = rac{F imes r^2}{m1 imes m2} $$. The unit of force (F) is Newton (N), the unit of distance (r) is meter (m), and the unit of mass (m) is kilogram (kg). Therefore, the unit of G is: $$ [G] = rac{N imes m^2}{kg^2} $$, which simplifies to $$ N m^2 kg^{-2} $$.

The Stefan-Boltzmann constant (σ) is used in the Stefan-Boltzmann law, which relates the total energy radiated per unit surface area of a black body to the fourth power of its temperature (T). The law is expressed as: $$ E = ext{σ} T^4 $$. Here, E is the energy radiated per unit area per unit time, which has the unit of watts per square meter ( ext{W m}^{-2}). To find the unit of σ, we rearrange the equation: $$ ext{σ} = rac{E}{T^4} $$. Since E has the unit of ext{W m}^{-2} and T has the unit of Kelvin (K), the unit of σ is: $$ ext{σ} = rac{W m^{-2}}{K^4} $$, which simplifies to $$ W m^{-2} K^{-4} $$.

Momentum (p) is defined as the product of mass (m) and velocity (v). Mathematically, it is given by: $$ p = m v $$. The unit of mass (m) is kilogram (kg) and the unit of velocity (v) is meter per second ( ext{m/s}). Therefore, the unit of momentum is: $$ [p] = kg imes rac{m}{s} $$, which is also known as a newton-second (N·s).

A light year is a unit of distance. It is defined as the distance that light travels in one year in a vacuum. Light travels at a speed of approximately 299,792,458 meters per second, so in one year, it covers a vast distance. This unit is often used in astronomy to measure the vast distances between stars and galaxies.

The SI unit of momentum is $ kg imes m imes s^{-1} $. Momentum is the product of mass and velocity, where mass is measured in kilograms (kg) and velocity in meters per second (m/s). Hence, the unit of momentum is $ kg imes ms^{-1} $.

Volt per meter (V/m) is the unit of electric field intensity. The electric field intensity is defined as the force experienced by a unit positive charge placed in the field. It can be derived from the potential difference (voltage) divided by the distance (meter).