## JEE Main Previous Year Papers Questions With Solutions Physics Units, Dimensions And Errors

Multiple Choice with ONE correct answer

1.In the formula X = 3YZ2, X and Z have  dimensions of capacitance and magnetic induction respectively. What are the dimensions of Y in MKSQ system ?     [1995-2 marks] Ans.  Ans.  (a)resistance                               (b) charge
(c) voltage                                    ( d) current
Ans.  Ans.  Ans.  6.A wire of length 1 = 6 ±0.06cm and radius r = 0.5 ± 0.005cm and mass m = 0.3 ± 0.003g . Maximum percentage error in density is  [2004-2 marks]
(a) 4    (b) 2      ( c) 1     ( d) 6.8
Ans.  7.Which of the following sets have different  dimensions ?  [2005-2 marks]
(a)Pressure, Young’s modulus, stress
(b)Emf, potential difference, electric potential
(c)Heat, work done, energy
(d)Dipole moment, electric flux, electric field
Ans. 8.The density of a solid ball is to be determined in  an experiment. The diameter of the ball is measured with a screw gauge, whose pitch is 0.5 mm and there are 50 divisions on the circular scale. The reading on the main scale is 2.5 mm and that on the circular scale is 20 divisions. If the measured mass of the ball has a relative error of 2%, the relative percentange error in the density is
(a) 0.9%           (b) 2.4%   (c) 3.1%   (d) 4.2%
Ans.
< Multiple Choice with ONE or  More Than ONE correct answers

9.If L,C,R represent inductance, capacitance and resistance respectively, the combinations having dimensions of frequency are [1984-2 marks] Ans. 10.Which of the following combinations have the dimensions of time ? L,C,R represent inductance, capacitance and resistance respectively  [1986-2 marks] Ans. 11.The dimensions of the quantities in one (or more) of the following pairs are the same. Identify the pair(s)         [1986-2 marks]
(a) Torque and work                           (b) Angular momentum and work
(c) Energy and Young’s modulus     (d) Light year and wavelength
Ans. 12.The dimensions of length are expressed as Gxcyhz .where G,c and h are the universal gravitational constant, speed of light and Planck’s constant respectively, then                 [1992-2 marks] Ans. 13.The pairs of physical quantities that have the same  dimensions in (are)  [1995-2   marks]
(a)Reynolds number and coefficient of friction
(b)Curie and frequency of a light wave
(c)Latent heat and gravitational potential
(d)Planck’s constant and torque
Ans.  Ans. 15.The ST unit of inductance, the henry can be written  as  [1998-2   marks]
(a)weber/ampere       (b)           volt-sec/amp
(c) joule/(ampere)2    (d) ohm-second
Ans. Matching Type

16.Match the physical quantities given in Column 1 with dimensions expressed in terms of mass (M), length (L), time (T), and charge (Q) given in Column II Ans. 17.Column-I gives three physical quantities. Select the appropriate units for the choices given in Column-II. Some of the physical quantities may have more than one choice correct  [1990-3 marks] Ans. 18.Some physical quantities are given in column I and some possible SI units in which these quantities may be expressed are given in Column II. Match the physical quantities in column I with the units in Column II. [2007-6 marks] Ans.  Subjective / Numerical integer type

19.Give the MKS units for each of the following  quantities :    [1980-3 marks]
i) Young’s modulus ii) Magnetic induction iii) Power of a lens
Ans. 20.A gas bubble, from an explosion under water,  oscillates with a period T proportional to padbEc • Where P is the static pressure, d is the density of water and E is the total energy of the explosion. Find the values of a,b and c         [1981-3 marks]
Ans. 21.Write the dimensions of the following in terms of mass, time, length and charge
i) magnetic flux ii) rigidity modulus  [1982-2 marks]]
Ans. Fill in the blanks

22.Planck’s constant has dimensions…………… [1985-2 marks]
Ans. 23.In the formula X = 3YZ2,X and Z have dimensions of capacitance and magnetic induction respectively. The dimensions of Y in MKSQ system  are………………………………. [1988-2 marks]
Ans. 24.The dimensions of electrical conductivity is…………….  [1997-1 mark]
Ans.  Ans. 