1.3 Scalars and vectors Scalar: described by a single number with a unit, such as 1kg(mass), 105kg/m (density), 1A(electrical current Vector: has both magnitude and a direction such as E B/N Represe nt by: A: Unit vector A=/42=A1 B=A.C=-A1.3 Scalars and Vectors ◼ Scalar: described by a single number with a unit, such as 1kg(mass), 103kg/m3 (density), 1A(electrical current). ◼ Vector: has both magnitude and a direction, such as r v a E     , , , Represe nt by: A  A A A ˆ AA ˆ = =   M N A  A ˆ B  C  A :Unit vector ˆ B A C A     = , = −