E × B gives the direction of travel (Examples 8.1, 8.2)E × B से संचरण दिशा (उदाहरण 8.1, 8.2)E × B gives the direction of travel (Examples 8.1, 8.2)

NCERT Ex 8.1, 8.2 · Class 12 Physics · Chapter 8 · interactive diagram

Parts and what they mean

• E along +y (Ex 8.1) (E, +y की ओर (उदा. 8.1)) — Given: E = 6.3 ĵ V/m at that point and instant.
• B along +z (Ex 8.1) (B, +z की ओर (उदा. 8.1)) — B = E/c = 6.3/(3×10⁸) = 2.1×10⁻⁸ T, along +z because ĵ × k̂ = î (the direction of travel).
• Direction of travel +x (Ex 8.1) (संचरण दिशा +x (उदा. 8.1)) — The wave travels along +x, so E × B must point along +x.
• B along +y (Ex 8.2) (B, +y की ओर (उदा. 8.2)) — B_y = 2×10⁻⁷ sin(0.5×10³ x + 1.5×10¹¹ t) T.
• E along +z (Ex 8.2) (E, +z की ओर (उदा. 8.2)) — E_z = 60 sin(0.5×10³ x + 1.5×10¹¹ t) V/m; E₀ = cB₀ = 60 V/m.
• Direction of travel −x (Ex 8.2) (संचरण दिशा −x (उदा. 8.2)) — The phase is (kx + ωt), so the wave moves towards −x. Check: k̂ × ĵ = −î.

Original diagram drawn by Simple Learning Hub, based on NCERT Ex 8.1, 8.2. Report a mistake