JEE Main 2026 Apr 8 Shift 2, Physics Q1: Units And Dimensions

JEE Main2026Apr 8, Shift 2Physics

A new unit ( $α$ ) of length is chosen such that it is equal to the speed of light in vacuum. What is the distance between Venus and Earth in terms of $α$ units if light takes $6$ min. $40$ s to cover this distance ?

A
$200 α$
B
$400 α$
C
$300 α$
D
$500 α$

Solution

The unit is defined so that $α = c \cdot (1 s) = 3 \times 1 0^{8}$ m (numerically the speed of light times one second).

Time of travel: $6$ min $40$ s $= 400$ s.

Distance $= c \cdot t = (3 \times 1 0^{8}) (400)$ m, which in $α$ units is $\frac{c \cdot 400}{c \cdot 1} = 400 α$ .

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JEE Main 2026 Apr 8 Shift 2, Physics Q1: Units And Dimensions

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