JEE Advanced 2025 Paper 1, Physics Section 2 Q2: Units And Dimensions

JEE Advanced2025Paper 1Physics Section 2

Length, breadth and thickness of a strip having a uniform cross section are measured to be 10.5 cm, 0.05 mm, and 6.0 $μ$ m, respectively. Which of the following option(s) give(s) the volume of the strip in cm $^{3}$ with correct significant figures:

A
$3.2 \times 1 0^{- 5}$
B
$32.0 \times 1 0^{- 6}$
C
$3.0 \times 1 0^{- 5}$
D
$3 \times 1 0^{- 5}$

Solution

Convert each measurement to cm and count significant figures:

$L = 10.5$ cm (3 sig. figs.), $b = 0.05$ mm $= 0.005$ cm (1 sig. fig.), $t = 6.0 μ m = 6.0 \times 1 0^{- 4}$ cm (2 sig. figs.).

For a product, the result carries the smallest count of significant figures among the factors, which is 1.

$V = 10.5 \times 0.005 \times 6.0 \times 1 0^{- 4} = 3.15 \times 1 0^{- 5}$ cm $^{3}$

Rounded to 1 significant figure: $V = 3 \times 1 0^{- 5}$ cm $^{3}$ . Only option (D) is written with exactly one significant figure. Hence the correct answer is (D).

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JEE Advanced 2025 Paper 1, Physics Section 2 Q2: Units And Dimensions

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