query: How can the tangent vector to a beam of light be expressed in these 2 ways?
positive_passages.docid: 152252
positive_passages.text: Tangent vector of photon
negative_passages.docid: 114449
negative_passages.text: Gravitational slingshot of light using a black hole/massive object
negative_passages.docid: 129567
negative_passages.text: Tangential component of Electric field
negative_passages.docid: 44164
negative_passages.text: Light Travels in straight line even in gravity
negative_passages.docid: 99590
negative_passages.text: Can the Lorentz force expression be derived from Maxwell's equations?
negative_passages.docid: 51253
negative_passages.text: Graphical intuition behind directional derivative interpreted as a(∂f/∂x)+b(∂f/∂y), where  is directional vector of unit length?
negative_passages.docid: 39159
negative_passages.text: Finding unit tangent, normal, and binormal vectors for a given r(t)
negative_passages.docid: 27825
negative_passages.text: Bending of light - photon's inertia instead of mass
negative_passages.docid: 18144
negative_passages.text: Does a nonzero Poynting vector mean that there is propagation of energy?
negative_passages.docid: 38712
negative_passages.text: Diffraction by a lens
negative_passages.docid: 34475
negative_passages.text: Spherical mirror ray diagram question
negative_passages.docid: 12923
negative_passages.text: How can tangential acceleration from a radial force be explained?
negative_passages.docid: 83301
negative_passages.text: Intuition behind directional derivative (geometrically)?
negative_passages.docid: 133756
negative_passages.text: Geometric interpretation of $\det(A^T) = \det(A)$
negative_passages.docid: 56079
negative_passages.text: Do two beams of light attract each other in general theory of relativity?
negative_passages.docid: 128327
negative_passages.text: Why does light bend towards the normal when passing from a rarer to a denser medium?
negative_passages.docid: 31156
negative_passages.text: Is light amplitude spatial?