Skip to content

#units

18 public questions tagged with this topic.

A physical quantity is expressed as Q = k v^a m^b t^c, where v is velocity, m is mass, t is time, and [Q] = [M L T^{-1]

Given: A physical quantity is expressed as Q = k v^a m^b t^c, where v is velocity, m is mass, t is time, and [Q] = [M L T^{-1] . Find a, b, c . These values define the system as per NCERT data. Formula: [v] = [L T^{-1], [m] = [M], [t] = [T]. This is standard NCERT relation. Substitution & Calculation: [Q] = [L T^{-1]^a [M]^b [T]^c = [M^b L^a T^{-a+c] . Equate: b = 1, a = 1, -a + c = -1 . -1 + c = -1 Rightarrow c = 0 . a = 1, b = 1, c = 0 . Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Relevant Physics topic covering fundamental principles,

What is the SI unit of frequency?

Frequency, the number of waves passing a point per second, is measured in hertz (Hz), where 1 Hz = 1 s^{-1. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

What is the SI unit of a quantity with dimensional formula [M L^{-1 T^{-2] ?

Given: What is the SI unit of a quantity with dimensional formula [M L^{-1 T^{-2] ? Formula: [M] = kg, [L] = m, [T] = s. Substitution & Calculation: [M L^{-1 T^{-2] = kg m^{-1 s^{-2 . (Pressure = [M L^{-1 T^{-2], unit = Pa). Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Physics Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII, continuing as per NCERT advisory for 2026-27),Topic: Fundamental laws, definitions and applications as per latest NCERT. The section explains governing laws, formulas like μ₀ = 4π.

What is the SI unit of a quantity with dimensional formula [M L T^{-1] ?

Given: What is the SI unit of a quantity with dimensional formula [M L T^{-1] ? These values define the system as per NCERT data. Formula: [M] = kg, [L] = m, [T] = s. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: [M L T^{-1] = kg m s^{-1 . (Matches momentum or impulse). Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Units and Measurements and Physical World, Topic: Dimensional analysis and fundamental principles.

What is the SI unit of a physical quantity with dimensional formula [M L² T^{-2 K^{-1 mol^{-1] using only base units?

Given: What is the SI unit of a physical quantity with dimensional formula [M L² T^{-2 K^{-1 mol^{-1] using only base units? Formula: Base units: [M] = kg, [L] = m, [T] = s, [K] = K, [mol] = mol. Substitution & Calculation: [M L² T^{-2 K^{-1 mol^{-1] = kg m² s^{-2 K^{-1 mol^{-1 . (Matches gas constant). Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Physics Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII, continuing as per NCERT advisory for 2026-27),Topic: Fundamental laws, definitions and applications as per latest NCERT. The section explains governing laws, formulas like μ₀ = 4π.

What is the SI unit of a quantity with dimensional formula [M L² T^{-3 A^{-1] ?

Given: What is the SI unit of a quantity with dimensional formula [M L² T^{-3 A^{-1] ? These values define the system as per NCERT data. Formula: [M] = kg, [L] = m, [T] = s, [A] = A. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: [M L² T^{-3 A^{-1] = kg m² s^{-3 A^{-1 . (Matches electric potential: Volt = W/A = kg m² s^{-3 A^{-1 ). Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Electric Charges and Fields and Electrostatic Potential, Topic: Electric field, potential and capacitance concepts.

Which of the following has the dimensional formula \[M0L0T0\]?

Dimensionless quantities like refractive index, strain, and angles have no physical dimensions. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Strain is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

If the unit of length is doubled, how is the unit of area affected?

Area is proportional to the square of length. So, if the unit of length doubles, the unit of area becomes four times larger. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Four times is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

Which one of the following pairs has different dimensions?

Pressure and stress both share the same dimensional formula \[ML−1T−2\], but energy has \[ML2T−2\]. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Pressure and Energy is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

Which of the following quantities has different dimensions?

Pressure has the dimensional formula \[ML−1T−2\] while the others represent forms of energy or work. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Pressure is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

Which of the following is a dimensionless constant?

Refractive index is the ratio of two similar quantities (speed of light), making it dimensionless. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Refractive index is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

Which of the following pairs have the same dimensions?

Torque and work both have the dimensional formula \[ML2T−2\]. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Work and Torque is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae