Question

If 2mi+2mj is a unit vector, then the value of ‘m’ is A. 1/9 B.1/4 C.1/3 D.1/2

Answer 1

Vector = 2m i + 2m j. Its magnitude is sqrt((2m)^2+(2m)^2) = 2|m|√2. For a unit vector:

2|m|√2 = 1 ⇒ |m| = 1/(2√2) = √2/4.

So m = ±1/(2√2) (= ±√2/4) — none of the given options (1/9, 1/4, 1/3, 1/2) is correct.