Physical World, Units & Measurements Biology | Chemistry | Physics | NTA Please enter your email: Parsec is the unit of (a) time (b) distance (c) frequency (d) angular acceleration The dimensions of Planck’s constant are (a) [ML–3T–1] (b) [ML–2T–1] (c) [M0L–1T–3] (d) [ML2T–1] If the capacitance of a nanocapacitor is measured in terms of a unit ‘u‘ made by combining the electric charge ‘e‘, Bohr radius ‘ao‘, Planck’s constant ‘h‘ and speed of light ‘c‘ then (a) u=e2h/ao (b) u=hc/e2ao (c) u=e2c/hao (d) u=e2ao/hc The dimensional formula for torque is (a) ML2T–2 (b) ML–1T–1 (c) L2T–1 (d) M2T–2K–1 The mass of the liquid flowing per second per unit area of cross-section of the tube is proportional to (pressure difference across the ends)n and (average velocity of the liquid)n. Which of the following relations between m and n is correct? (a) m = n (b) m = – n (c) m2 = n (d) m = – n2 The siemen is the SI unit of (a) resistivity (b) resistance (c) conductivity (d) conductance The density of material in CGS system of units is 4g/cm3. In a system of units in which unit of length is 10 cm and unit of mass is 100 g, the value of density of material will be (a) 0.4 unit (b) 40 unit (c) 400 unit (d) 0.04 unit The dimensions of Reynold’s constant are (a) [M0L0T0] (b) [ML–1T–1] (c) [ML–1T–2] (d) [ML–2T–2] The time period of a body under S.H.M. is represented by: T = Pa Db Sc where P is pressure, D is density and S is surface tension, then values of a, b and c are (a) –3⁄2, 1⁄2, 1 (b) –1, –2, 3 (c) 1⁄2, –3⁄2, –1⁄2 (d) 1, 2, 1⁄3 Unit of magnetic moment is (a) ampere–metre2 (b) ampere–metre (c) weber–metre (d) weber/metre If e is the charge, V the potential difference, T the temperature, then the units of eV /T are the same as that of (a) Planck’s constant (b) Stefan’s constant (c) Boltzmann’s constant (d) gravitational constant The dimensional formula of farad is (a) [M–1L–2TQ] (b) [M–1L–2T2Q2] (c) [M–1L–2TQ2 ] (d) [M–1L–2T2Q] Young’s modulus of a material has the same unit as that of (a) pressure (b) strain (c) compressibility (d) force The dimensions of 1/εo e2/hc are (a) M-1 L-3 T4 A2 (b) ML3 T-4 A-2 (c) M0 L0 T0 A0 (d) M-1 L-3 T2 A Which of the following is a dimensional constant? (a) Refractive index (b) Poissons ratio (c) Strain (d) Gravitational constant Dimensions of electrical resistance are (a) [ML2T–3A–1] (b) [ML2T–3A–2] (c) [ML3T–3A–2] (d) [ML–1L3T3A2] If velocity (V), force (F) and energy (E) are taken as fundamental units, then dimensional formula for mass will be (a) V-2F0E (b) V0FE2 (c) VF–2E0 (d) V-2F0E The dimensional formula for magnetic flux is (a) [ML2T–2A–1] (b) [ML3T–2A–2] (c) [M0L–2T2A–2] (d) [ML2T–1A2] The speed of light (c), gravitational constant (G) and planck’s constant (h) are taken as fundamental units in a system. The dimensions of time in this new system should be (a) G1/2 h1/2 c–5/2 (b) G–1/ 2 h1/ 2 c1/ 2 (c) G1/ 2 h1/ 2 c–3/ 2 (d) G1/ 2 h1/ 2 c1/ 2 If Q denote the charge on the plate of a capacitor of capacitance C then the dimensional formula for Q2/C is (a) [L2M2T] (b) [LMT2] (c) [L2MT–2] (d) [L2M2T2] Two quantities A and B have different dimensions which mathematical operation given below is physically meaningful? (a) A/B (b) A + B (c) A – B (d) A = B The dimensions of 1⁄2 ε0E2 ( ε0 : permittivity of free space, E electric field) are (a) [MLT–1] (b) [ML2T–2] (c) [ML–1T–2] (d) [ML2T–1] A quantity X is given by εoL ΔV⁄Δt where εo is the permittivity of the free space, L is a length, ΔV is a potential difference and Δt is a time interval. The dimensional formula for X is the same as that of (a) resistance (b) charge (c) voltage (d) current In a vernier callipers, ten smallest divisions of the vernier scale are equal to nine smallest division on the main scale. If the smallest division on the main scale is half millimeter, then the vernier constant is (a) 0.5 mm (b) 0.1 mm (c) 0.05 mm (d) 0.005 mm The pressure on a square plate is measured by measuring the force on the plate and length of the sides of the plate by using the formula P = F/l2. If the maximum errors in the measurement of force and length are 4% and 2% respectively, then the maximum error in the measurement of pressure is (a) 1% (b) 2% (c) 8% (d) 10% What is the dimensional formula of gravitational constant? (a) [ML2T–2 ] (b) [ML–1T–1] (c) [M–1L3T–2 ] (d) none of these The respective number of significant figures for the numbers 23.023, 0.0003 and 2.1 × 10-3 are (a) 5, 1, 2 (b) 5, 1, 5 (c) 5, 5, 2 (d) 4, 4, 2 An experiment is performed to obtain the value of acceleration due to gravity g by using a simple pendulum of length L. In this experiment time for 100 oscillations is measured by using a watch of 1 second least count and the value is 90.0 seconds. The length L is measured by using a meter scale of least count 1 mm and the value is 20.0 cm. The error in the determination of g would be: (a) 1.7% (b) 2.7% (c) 4.4% (d) 2.27% The unit of impulse is the same as that of (a) energy (b) power (c) momentum (d) velocity Which is different from others by units? (a) Phase difference (b) Mechanical equivalent (c) Loudness of sound (d) Poisson’s ratio What is the fractional error in g calculated from T = 2π √l/ g? Given fraction errors in T and l are ± x and ± y respectively? (a) x + y (b) x – y (c) 2x + y (d) 2x – y Dimensions of coefficient of viscosity is (a) [MT2] (b) [ML–3T–4] (c) [ML–1T–2] (d) [ML–1T–1] The dimensional formula of magnetic flux is (a) [ML0T–2A–1] (b) [ML2T–2A–1] (c) [ML2T–1A3] (d) [M0L–2T–2A–2] The length and breadth of a metal sheet are 3.124 m and 3.002 m respectively. The area of this sheet upto four correct significant figure is (a) 9.378 m2 (b) 9.37 m2 (c) 9.378248 m2 (d) 9.3782 m2 The density of a cube is measured by measuring its mass and length of its sides. If the maximum error in the measurement of mass and length are 4% and 3% respectively, the maximum error in the measurement of density will be (a) 7% (b) 9% (c) 12% (d) 13% Velocity of light is equal to (a) √(1 /ε0μ0) (b) √(ε0 / μ0) (c) ε0 / μ0 (d) ε0μ The dimensional formula of the constant a in Vander Waal’s gas equation(P+a⁄V2)(V-b)=RT is (a) [ML4T–1] (b) [ML2T–2 ] (c) [ML5T–3 ] (d) [ML5T–2 ] An object is moving through the liquid. The viscous damping force acting on it is proportional to the velocity. Then dimensions of constant of proportionality are (a) [ML-1T-1] (b) [MLT-1] (c) [M0LT-1] (d) [ML0T-1] The Richardson equation is given by I=AT2e—B/kT. The dimensional formula for AB2 is same as that for (a) I T2 (b) kT (c) I k2 (d) I k2/T The dimensions of energy are (a) [ML3T–3] (b) [ML–1T–1] (c) [ML2T–2] (d) [MT–2] The physical quantity which has the dimensional formula [M1T-3] is (a) surface tension (b) solar constant (c) density (d) compressibility Which of the following pairs does not have similar dimensions? (a) tension and surface tension (b) stress and pressure (c) Planck’s constant and angular momentum (d) angle and strain The magnetic moment has dimensions of (a) [LA] (b) [L2A] (c) [LT–1A] (d) [L2T–1A] The least count of a stop watch is 0.2 second. The time of 20 oscillations of a pendulum is measured to be 25 second. The percentage error in the measurement of time will be (a) 8% (b) 1.8% (c) 0.8% (d) 0.1% A force F is applied onto a square plate of side L. If the percentage error in determining L is 2% and that in F is 4%, the permissible percentage error in determining the pressure is (a) 2% (b) 4% (c) 6% (d) 8% Loading … Question 1 of 45
