Test: Units & Measurement - 1 - JEE MCQ

Torque = Work = Energy =[ML²T^-2]


 

(i) All the non-zero digits are significant. 
(ii) All the zeros between two non-zero digits are significant, no matter where the decimal point is, if at all.
 (iii) If the number is less than 1, the zero(s) on the right of decimal point but to the left of the first non-zero digit are not significant. 
(iv) The power of 10 is irrelevant to the determination of significant figures. According to the above rules, 23.023 has 5 significant figures. 0.0003 has 1 significant figures. 2.1 × 10^–3 has 2 significant figures.

Unit of K is joules per kelvin or the dimensional formula of Kis [ML²T^-2θ^-1].

αz/kθ should be dimensionless,
So, dimensional formula of α = [ML²T^-2]/[L] = MLT^-2
Dimensional formula of P = [ML^-1T^-2]
rArr β = [α/P]

= [MLT^-2]/[ML^-1T^-2]
= M⁰L²T⁰

Dipole moment:

1. A dipole moment arises whenever a separation between the system
2. The formula of the dipole moment
   
3. The dimension formula for
   

Electric field intensity:

1. The electric field intensity is the strength of the electric field at the point
2. It is the force experienced by the unit positive charge in that point
   

where, F represents force, and the q₀ is the test charge.

        3. The dimension formula for Electric field intensity

Electric flux

1. The electric flux around an area inside an electric field is the total lines of forces passing through that area.
2. The equation of the electric flux:
   
3. The dimension formula for Electric flux
   

Hence, Option D is the correct answer.

An electron volt (eV) is a unit of energy, not charge, potential difference, or momentum.

1. Definition of Electron Volt (eV):
   An electron volt is defined as the amount of energy gained (or lost) by an electron when it is accelerated through an electric potential difference of one volt.

2. Conversion to Joules:
   1eV=1.602×10⁻¹⁹J

3. Why eV is Energy:
   Since energy is defined as the work done or potential energy change, moving an electron through a potential difference of one volt results in an energy change. Thus, the electron volt is a convenient unit of energy, especially in atomic and particle physics where energies are relatively small and often on the order of eV.

The electron volt (eV) is a unit of energy, and it is widely used in physics to measure small energy values, especially at the atomic or subatomic scale.

So, the answer is: (4) Energy