-**Vector product**: in addition to multiplying a vector by a scalar, as mentioned above, one can also multiply two vectors among them.
!!! info "Vector product"
There are two types of vector productions, one where the end result is a scalar (so just a number) and
In addition to multiplying a vector by a scalar, as mentioned above, one can also multiply two vectors among them.
the other where the end result is another vectors.
There are two types of vector productions, one where the end result is a scalar (so just a number) and the other where the end result is another vectors.
- The **scalar production of vectors** is given by $$ \vec{a}\cdot \vec{b} = a_1b_1 + a_2b_2 + \ldots + a_nb_n \, .$$
!!! info "The scalar production of vectors"
Note that since the scalar product is just a number, its value will not depend on the specific
The **scalar production of vectors is given by $$ \vec{a}\cdot \vec{b} = a_1b_1 + a_2b_2 + \ldots + a_nb_n \, .$$
basis in which we express the vectors: the scalar product is said to be *basis-independent*. The scalar product is also found via
Note that since the scalar product is just a number, its value will not depend on the specific
where $|\vec{a}|=\sqrt{ \vec{a}\cdot\vec{a} }$ (and likewise for $|\vec{b}|$) is the norm of the vector $\vec{a}$, $\theta$ is the angle between the two vectors, and $\hat{n}$ is a unit vector which is *perpendicular* to the plane that contains $\vec{a}$ and $\vec{b}$.
where $|\vec{a}|=\sqrt{ \vec{a}\cdot\vec{a} }$ (and likewise for $|\vec{b}|$) is the norm of the vector $\vec{a}$, $\theta$ is the angle
Note that this cross-product can only be defined in *three-dimensional vector spaces*. The resulting vector
between the two vectors, and $\hat{n}$ is a unit vector which is *perpendicular* to the plane that contains $\vec{a}$ and $\vec{b}$.
$\vec{c}=\vec{a}\times \vec{b} $ will have as components $c_1 = a_2b_3-a_3b_2$, $c_2= a_3b_1 - a_1b_3$, and $c_3= a_1b_2 - a_2b_1$.
Note that this cross-product can only be defined in *three-dimensional vector spaces*. The resulting vector $\vec{c}=\vec{a}\times \vec{b} $ will have as components $c_1 = a_2b_3-a_3b_2$, $c_2= a_3b_1 - a_1b_3$, and $c_3= a_1b_2 - a_2b_1$.
- A special vector is the **unit vector**, which has a norm of 1 *by definition*. A unit vector is often denoted with a hat, rather than an arrow ($\hat{i}$ instead of $\vec{i}$). To find the unit vector in the direction of an arbitrary vector $\vec{v}$, we divide by the norm:
- A special vector is the **unit vector**, which has a norm of 1 *by definition*. A unit vector is often denoted with a hat, rather than an arrow ($\hat{i}$ instead of $\vec{i}$). To find the unit vector in the direction of an arbitrary vector $\vec{v}$, we divide by the norm: