In spherical polar coordinates (γ, θ, α), θ denotes the polar angle ar

In spherical polar coordinates (γ, θ, α), θ denotes the polar angle around z-axis and α denotes the azimuthal angle raised from x-axis. Then the y-component of P⃗ is given by

Psinθsinα
Psinθcosα
Pcosθsinα
Pcosθcosα
This question was previously asked in
UPSC CDS-1 – 2019
In spherical polar coordinates (γ, θ, α), where γ is the magnitude of the vector P⃗ (let’s denote it as P), θ is the polar angle from the positive z-axis, and α is the azimuthal angle from the positive x-axis in the xy-plane, the Cartesian components (Px, Py, Pz) of the vector P⃗ are given by:
$P_x = P \sin\theta \cos\alpha$
$P_y = P \sin\theta \sin\alpha$
$P_z = P \cos\theta$
The question asks for the y-component of P⃗. According to the standard conversion from spherical to Cartesian coordinates, the y-component is $P\sin\theta\sin\alpha$.
– Spherical coordinates typically use (r, θ, φ) or (ρ, θ, φ). The question uses (γ, θ, α) with meanings specified.
– γ (or P) is the magnitude.
– θ is the angle from the z-axis (polar angle).
– α is the angle from the x-axis in the xy-plane (azimuthal angle).
– The projection onto the xy-plane has length $P\sin\theta$.
– This projection is resolved into x and y components using the azimuthal angle α.
The formulas for converting spherical coordinates (P, θ, α) to Cartesian coordinates (Px, Py, Pz) are derived from trigonometry. The projection of the vector onto the z-axis is $P\cos\theta$, giving the z-component. The projection onto the xy-plane has length $P\sin\theta$. This projection forms a right triangle in the xy-plane with the x and y axes, where the hypotenuse is $P\sin\theta$ and the angle with the x-axis is α. The x-component is $(P\sin\theta)\cos\alpha$ and the y-component is $(P\sin\theta)\sin\alpha$.
Exit mobile version