99 Percentile Qs Bank for JEE MainPhysicsElectromagnetic Waves
When two different materials A and B having atomic number Z 1 and Z 2 are used as the target in Coolidge γ -ray tube at different operating voltage V 1 and V 2 respectively their spectrums are found as below. The correct relation is
Options
- AV 1 > V 2 and Z 1 > Z 2
- BV 1 < V 2 and Z 1 < Z 2
- CV 1 < V 2 and Z 1 > Z 2
- DV 1 > V 2 and Z 1 < Z 2
Correct answer
D. V 1 > V 2 and Z 1 < Z 2
Step-by-step solution
λ m i n = h c e V ⇒ λ ∝ 1 V ∵ λ 2 > λ 1 (see graph) ⇒ V 1 > V 2 f = a Z - b Moseley's law f ∝ Z - 1 2 ⇒ λ ∝ 1 Z - 1 2 ( ∵ f ∝ 1 λ ) λ 1 > λ 2 (see graph for characteristic lines) ⇒ Z 2 > Z 1