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Units and Measurements · Question 23

JEE Main 2026 (Online) 23rd January Morning ShiftMCQEasy📈 Topic in 3% papers+4−1
1

Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01 cm and 18.25 cm. The relative error in the measurement of average length of the rod is :

  1. 0.18
  2. 0.24
  3. 0.06
  4. 0.08

Answer

(3) 0.06

Solution

Mean length l = 20.00 + 19.75 + 17.01 + 18.254 = 75.014 = 18.75 cm

Absolute errors: | li| = 1.25, 1.00, 1.74, 0.50 cm

Mean absolute error l = 1.25 + 1.00 + 1.74 + 0.504 = 4.494 1.12 cm

Relative error = l l = 1.1218.75 0.06

Answer: (3)

JEE Main 2026 (Online) 23rd January Morning Shift

Keep practising — Units and Measurements

2

A ball of radius r and density dropped through a viscous liquid of density and viscosity attains its terminal velocity at time t, given by t = A a rb c d, where A is a constant and a, b, c and d are integers. The value of b + ca + d is .

JEE Main 2026 (Online) 23rd January Evening Shift
3

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

  1. A-III, B-II, C-IV, D-I
  2. A-I, B-IV, C-II, D-III
  3. A-II, B-I, C-IV, D-III
  4. A-II, B-IV, C-I, D-III
JEE Main 2026 (Online) 22nd January Morning Shift
4

In an experiment the values of two spring constants were measured as k1 = (10 0.2) N/m and k2 = (20 0.3) N/m. If these springs are connected in parallel, then the percentage error in equivalent spring constant is :

  1. 1.33%
  2. 2.67%
  3. 1.67%
  4. 2.33%
JEE Main 2026 (Online) 21st January Morning Shift
5

Consider a modified Bernoulli equation. (P + ABt2 ) + g(h + Bt) + 12 V2 = constant If t has the dimension of time then the dimensions of A and B are , respectively.

  1. [ ML0T-1] and [M0LT]
  2. [ ML0T-2] and [ M0LT-1]
  3. [ ML0T-2] and [ M0LT-2]
  4. [ ML0T-1] and [ M0LT-1]
JEE Main 2026 (Online) 21st January Morning Shift
6

A spherical body of radius r and density falls freely through a viscous liquid having density and viscosity and attains a terminal velocity v0. Estimated maximum error in the quantity is : (Ignore errors associated with , and g, gravitational acceleration)

  1. 2 [ rr - v0v0 ]
  2. 2 [ rr + v0v0 ]
  3. 2 rr + v0v0
  4. 2 rr - v0v0
JEE Main 2026 (Online) 21st January Evening Shift
7

Keeping the significant figures in view, the sum of the physical quantities 52.01 m, 153.2 m and 0.123 m is :

  1. 205.3 m
  2. 205 m
  3. 205.333 m
  4. 205.33 m
JEE Main 2026 (Online) 21st January Evening Shift
8

A quantity Q is formulated as X-2Y+ 32Z- 25. X, Y, and Z are independent parameters which have fractional errors of 0.1, 0.2, and 0.5, respectively in measurement. The maximum fractional error of Q is

  1. 0.6
  2. 0.8
  3. 0.7
  4. 0.1
JEE Main 2025 (Online) 8th April Evening Shift
9

The dimension of 0 0 is equal to that of: ( 0 = Vacuum permeability and 0 = Vacuum permittivity)

  1. Voltage
  2. Inductance
  3. Resistance
  4. Capacitance
JEE Main 2025 (Online) 7th April Evening Shift
10

Match List - I with List - II. Choose the correct answer from the options given below :

  1. (A)-(IV), (B)-(II), (C)-(III), (D)-(I)
  2. (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
  3. (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
  4. (A)-(IV), (B)-(II), (C)-(I), (D)-(III)
JEE Main 2025 (Online) 7th April Evening Shift
11

In an electromagnetic system, the quantity representing the ratio of electric flux and magnetic flux has dimension of MP LQ TR AS, where value of 'Q' and 'R' are

  1. (3, -5)
  2. (-2, 1)
  3. (-2, 2)
  4. (1, -1)
JEE Main 2025 (Online) 4th April Morning Shift

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