If Planck's constant (h) and the speed of light in vacuum (c) are taken as fundamental units, then the dimension of time (T) is:

5 views 0 helpful Updated Jul 27, 2026
Appears in NEET UG
Solution ✔ Verified
  • Ah c^-1
  • Bh c^-2
  • Ch c²
  • Dh c^-3
Explanation

We need to find x, y such that [T] = [h]^x [c]^y. Dimensions: [h] = [M L² T^-1], [c] = [L T^-1]. This system is incomplete as it lacks a mass dimension to define T in terms of h and c alone without M. Let's re-examine this. Usually, these questions involve three fundamental units. If only two, it might mean the other fundamental units cancel out. Let's try: [T] = [h]^x [c]^y. 1. Power of M: 0 = x 2. Power of L: 0 = 2x + y 3. Power of T: 1 = -x - y From (1), x=0. Then from (2), y=0. Then from (3), 1 = 0, which is impossible. This implies that Time cannot be solely defined by h and c if mass is involved.

Was this solution helpful?
0
Practice MCQs on Units & Dimensions — test yourself with instant answers. Start Practising