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Units and Measurements

JEE Main 2025 (Online) 29th January Evening ShiftNumericalEasy📈 Topic in 33% papers+4
Ques. 1JEE Main 2025, 29 January (Evening Shift)

A physical quantity Q is related to four observables a, b, c, d as follows : Q= ab4cd where, a=(60 3) Pa; b=(20 0.1) m; c=(40 0.2) N s m-2 and d=(50 0.1) m, then the percentage error in Q is x1000, where x= .

Answer

7700

Solution

Product/quotient ⇒ QQ= aa+4 bb+ cc+ dd

=5\%+4(0.5\%)+0.5\%+0.2\%=7.7\%

= 77001000 ⇒ x=7700

Answer: 7700

Keep practising — Units and Measurements

Ques. 2JEE Main 2025, 28 January (Morning Shift)

In a measurement, it is asked to find modulus of elasticity per unit torque applied on the system. The measured quantity has dimension of [MaLbTc]. If b = -3, the value of c is .

Ques. 3JEE Main 2025, 28 January (Morning Shift)

A tiny metallic rectangular sheet has length and breadth of 5 mm and 2.5 mm, respectively. Using a specially designed screw gauge which has pitch of 0.75 mm and 15 divisions in the circular scale, you are asked to find the area of the sheet. In this measurement, the maximum fractional error will be x100 where x is .

Ques. 4JEE Main 2025, 28 January (Evening Shift)

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

  1. (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
  2. (A)-(I), (B)-(III), (C)-(IV), (D)-(II)
  3. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
  4. (A)-(III), (B)-(I), (C)-(II), (D)-(IV)
Ques. 5JEE Main 2025, 24 January (Morning Shift)

For an experimental expression y= 32.3 112527.4, where all the digits are significant. Then to report the value of y we should write

  1. y=1326.186
  2. y=1326.2
  3. y=1326.19
  4. y=1330
Ques. 6JEE Main 2025, 24 January (Morning Shift)

The least count of a screw gauge is 0.01 mm. If the pitch is increased by 75% and number of divisions on the circular scale is reduced by 50%, the new least count will be 10-3 mm.

Ques. 7JEE Main 2025, 24 January (Evening Shift)

The energy E and momentum p of a moving body of mass m are related by some equation. Given that c represents the speed of light, identify the correct equation

  1. E2=pc2+m2c4
  2. E2=pc2+m2c2
  3. E2=p2c2+m2c4
  4. E2=p2c2+m2c2
Ques. 8JEE Main 2025, 23 January (Morning Shift)

The position of a particle moving on x-axis is given by x(t)=A t+B 2t+Ct2+D, where t is time. The dimension of ABCD is

  1. L
  2. L3 T-2
  3. L2 T-2
  4. L2
Ques. 9JEE Main 2025, 23 January (Morning Shift)

The electric flux is = + where and are linear and surface charge density, respectively. ( ) represents

  1. displacement
  2. charge
  3. electric field
  4. area
Ques. 10JEE Main 2025, 23 January (Evening Shift)

The energy of a system is given as E(t)= 3e- t, where t is the time and =0.3 s-1. The errors in the measurement of and t are 1.2\% and 1.6\%, respectively. At t=5 s, maximum percentage error in the energy is :

  1. 6\%
  2. 11.6\%
  3. 4\%
  4. 8.4\%
Ques. 11JEE Main 2025, 23 January (Evening Shift)

Match 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)-(III), (D)-(IV)
  4. (A)-(IV), (B)-(III), (C)-(I), (D)-(II)

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