JEE Main 2025 Apr 4 Shift 1, Physics Q8: Electromagnetic Waves

JEE Main2025Apr 4, Shift 1Physics

In an electromagnetic system, the quantity representing the ratio of electric flux and magnetic flux has dimension of $M^{P} L^{Q} T^{R} A^{S}$ , where value of $^{'} Q^{'}$ and $^{'} R^{'}$ are

A
$(3, - 5)$
B
$(- 2, 2)$
C
$(- 2, 1)$
D
$(1, - 1)$

Solution

For surfaces of equal area, $\frac{ϕ _{E}}{ϕ _{M}} = \frac{E \cdot A}{B \cdot A} = \frac{E}{B}$ .

From electromagnetic wave physics, $E = c B$ where $c$ is the speed of light, so $\frac{E}{B} = c$ has dimensions of speed: $[L T^{- 1}]$ .

Matching with $M^{P} L^{Q} T^{R} A^{S}$ : $P = 0, Q = 1, R = - 1, S = 0$ .

Therefore $(Q, R) = (1, - 1)$ .

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JEE Main 2025 Apr 4 Shift 1, Physics Q8: Electromagnetic Waves

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