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2 public questions tagged with this topic.

Applications of EM Waves in Communication and Medicine

What physical quantity is the same for all electromagnetic waves in vacuum?

**Radio waves** effective for long-distance communication because low frequency waves diffract around Earth curvature and reflect from ionosphere, enabling beyond line-of-sight, used in AM (≈10⁶ Hz) ground wave, short wave sky wave. Microwaves used for satellite due to high frequency penetrates ionosphere and directional beam. All electromagnetic waves in vacuum travel at the same speed, c = 3 × 10⁸ m/s , regardless of their frequency or wavelength. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Speed, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Applications of EM Waves in Communication and Medicine

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Motion in a Plane and Projectile Motion

In projectile motion, what remains constant throughout the trajectory, assuming no air resistance?

Projectile motion splits into horizontal uniform and vertical accelerated motion per NCERT Chapter 4. Range R=u²sin2θ/g and max height H=u²sin²θ/2g. Using given u, θ, g, calculation yields Horizontal velocity. Hence option B satisfies projectile formulas.

Ref: NCERT Class 11 Physics > Chapter 4: Motion in a Plane > Topic: Motion in a Plane and Projectile Motion

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