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Units and Measurements · Question 26

JEE Main 2026 (Online) 21st January Morning ShiftMCQEasy📈 Topic in 29% papers+4−1
1

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%

Answer

(3) 1.67%

Solution

Parallel combination: k = k1 + k2 = 10 + 20 = 30 N/m

In a sum, absolute errors add: k = k1 + k2 = 0.2 + 0.3 = 0.5 N/m

Percentage error = kk 100 = 0.530 100 = 1.67\%

Answer: (3)

JEE Main 2026 (Online) 21st January Morning Shift

Keep practising — Units and Measurements

2

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
3

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
4

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
5

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
6

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
7

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
8

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
9

In an electromagnetic system, a quantity defined as the ratio of electric dipole moment and magnetic dipole moment has dimension of [MP LQ TR AS ]. The values of P and Q are :

  1. -1, 0
  2. 0, -1
  3. -1, 1
  4. 1, -1
JEE Main 2025 (Online) 4th April Evening Shift
10

A person measures mass of 3 different particles as 435.42 g, 226.3 g and 0.125 g. According to the rules for arithmetic operations with significant figures, the addition of the masses of 3 particles will be.

  1. 661.845 g
  2. 661.84 g
  3. 662 g
  4. 661.8 g
JEE Main 2025 (Online) 3rd April Morning Shift
11

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

  1. A-IV, B-III, C-II, D-I
  2. A-II, B-IV, C-III, D-I
  3. A-I, B-III, C-IV, D-II
  4. A-III, B-II, C-I, D-IV
JEE Main 2025 (Online) 3rd April Morning Shift

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