Unit Vector - Formula, Definition, Caculate, Notation - Cuemath

Unit Vector

Vectors are geometric entities that have magnitude and direction. Vectors have a starting point and a terminal point which represents the final position of the point. Various arithmetic operations can be applied to vectors such as addition, subtraction, and multiplication. A vector that has a magnitude of 1 is termed a unit vector. For example, vector v = (1, 3) is not a unit vector, because its magnitude is not equal to 1, i.e., |v| = √(12+32) ≠ 1.

Any vector can become a unit vector when we divide it by the magnitude of the same given vector. A unit vector is also sometimes referred to as a direction vector. Let us learn more about the unit vector, its formula along with a few solved examples.

1.	What is Unit Vector?
2.	Unit Vector Notation
3.	Unit Vector Formula
4.	How to Calculate the unit vector?
5.	Application of Unit Vector
6.	Properties of Vectors
7.	Solved Examples
8.	Practice Questions on Unit Vector
9.	FAQs on Unit Vector

What is Unit Vector?

A unit vector is a vector that has the magnitude equal to 1. The unit vectors are denoted by the "cap" symbol ^. The length of unit vectors is 1. Unit vectors are generally used to denote the direction of a vector. A unit vector has the same direction as the given vector but has a magnitude of one unit; For a vector A; a unit vector is; \(\hat{A}\) and \(\hat{A} = (1/|A|)\hat{A}\)

i, j, and k are the unit vectors in the directions of the x-axis, y-axis, and z-axis respectively in a 3-dimensional plane. i.e.,

• |i| = 1
• |j| = 1
• |k| = 1

Magnitude of a Vector

The magnitude of a vector gives the numeric value for a given vector. A vector has both a direction and a magnitude. The magnitude of a vector formula summarises the individual measures of the vector along the x-axis, y-axis, and z-axis. The magnitude of a vector A is |A|. For a given vector with the direction along the x-axis, y-axis, and z-axis, the magnitude of the vector can be obtained by calculating the square root of the sum of the squares of its direction ratios. Let us understand it clearly from the below magnitude of a vector formula.

For a vector A = ai + bj + ck its magnitude is: |A| = √(a2 + b2 + c2)

For example, if A = 1i + 2j + 3k, then |A| = √(12+22+22) = √9 = 3 units.

Unit Vector Notation

Unit Vector is represented by the symbol ‘^’, which is called a cap or hat, such as \(\hat{a}\). It is given by \(\hat{a}\) = a/|a| Where |a| is for norm or magnitude of vector a. It can be calculated using a unit vector formula or by using a calculator.

Unit vector in three-dimension

The unit vectors of i, j, and k are usually the unit vectors along the x-axis, y-axis, z-axis respectively. Every vector existing in the three-dimensional space can be expressed as a linear combination of these unit vectors. The dot product of two unit vectors is always a scalar quantity. On the other hand, the cross-product of two given unit vectors gives a third vector perpendicular (orthogonal) to both of them.

Unit Normal Vector

A 'normal vector' is a vector that is perpendicular to the surface at a defined point. It is also called “normal” to a surface containing the vector. The unit vector that is acquired after normalizing the normal vector is the unit normal vector, also known as the “unit normal.” For this, we divide a non-zero normal vector by its vector norm.

Unit Vector Formula

As vectors have both magnitude (value) and direction, they are shown with an arrow. In particular, \(\hat{a}\) denotes a unit vector. If we want to find the unit vector of any vector, we divide it by the vector's magnitude. Usually, the coordinates of x, y, z are used to represent any vector.

A vector can be represented in two ways:

1. a = (x, y, z) using the brackets.

2. a = xi + yj +zk

The formula for the magnitude of a vector is: |a|= √(x2 + y2 + z2)

The formula of unit vector in the direction of a given vector is:

• Unit Vector = Vector/Vector's magnitude

How to Calculate the unit vector?

To find a unit vector with the same direction as a given vector, simply divide the vector by its magnitude. For example, consider a vector v = (3, 4) which has a magnitude of |v|. If we divide each component of vector v by |v| to get the unit vector \(\hat{v}\) which is in the same direction as v.

|v| = √(32 + 42) = 5

Thus, \(\hat{v}\) = v / |v| = (3, 4) / 5 = (3/5, 4/5).

How to represent vector in a bracket format? If a = (x, y, z), then the unit vector in the direction of a in bracket format is, \(\hat{a}\) = a/|a| = (x,y,z)/√(x2 + y2 + z2) = ( x/ √(x2 + y2 + z2), y/√(x2 + y2 + z2), z/√(x2 + y2 + z2) )

How to represent vector in a unit vector component format? If a = xi + yj + zk is a vector then the unit vector in the direction of a in component format is, \(\hat{a}\) = a/|a| = (xi + yj + zk)/ √(x2 + y2 + z2) = x/√(x2 + y2 + z2) . i + y/√(x2 + y2 + z2) . j + z/√(x2 + y2 + z2) . k Where x, y, z represent the value of the vector along the x- axis, y-axis, z-axis respectively and \(\hat{a}\) is a unit vector, a is a vector, |a| is the magnitude of the vector, i, j, k are the directed unit vectors along the x, y, and z axes respectively.

Application of Unit Vector

Unit vectors specify the direction of a vector. Unit vectors can exist in both two and three-dimensional planes. Every vector can be represented with its unit vector in the form of its components. The unit vectors of a vector are directed along the axes.

In the 3-d plane, the vector v will be identified by three perpendicular axes (x, y, and z-axis). In mathematical notations, the unit vector along the x-axis is represented by i. The unit vector along the y-axis is represented by j, and the unit vector along the z-axis is represented by k.

The vector v can hence be written as:

v = xi + yj + zk

Electromagnetics deals with electric forces and magnetic forces. Here vectors come in handy to represent and perform calculations involving these forces. In day-to-day life, vectors can represent the velocity of an airplane or a train, where both the speed and the direction of movement are needed.

Properties of Vectors

The properties of vectors are helpful to gain a detailed understanding of vectors and also to perform numerous calculations involving vectors, A few important properties of vectors are listed here.

• A . B = B. A
• A × B ≠ B × A
• i . i = j . j = k . k = 1
• i . j = j . k = k . i = 0
• i × i = j × j = k × k = 0
• i × j = k; j × k = i; k × i = j
• j × i = -k; k × j = -i; i × k = -j
• The dot product of two vectors is a scalar and lies in the plane of the two vectors.
• The cross product of two vectors is a vector, which is perpendicular to the plane containing these two vectors.

☛ Related Topics:

• Vector Quantities
• Vector Subtraction Calculator
• Vector Formulas
• Dot Product Calculator

Important Notes on Unit Vectors:

• The dot product of orthogonal unit vectors is always zero.
• The cross product of parallel unit vectors is always zero.
• Two unit vectors are collinear if their cross product is zero.
• The norm of a vector is a real non-negative value that represents its magnitude.