Verified Solution β’ 2025β26 Session
hard
QJEEA-2024-11: JEE Advanced 2024 JEEA-2024-11 Solution: Q.11 A point source S emits unpolarized lightβ¦
Q.11 A point source S emits unpolarized light uniformly in all directions. At two points A and B, the ratio π = πΌπ΄/πΌπ΅ of the intensities of light is 2. If a set of two polaroids having 45Β° angle between their pass-axes is placed just before point B, then the new value of π will be .
Step-by-Step Verified Solution
Solution:
- Doppler Effect Formula:
- f' = f (v_sound Β± v_observer) / (v_sound Β± v_source)
- Where:
- f' = observed frequency
- f = source frequency
- v_sound = speed of sound
- v_observer = speed of observer
- v_source = speed of source
- Case 1 (Moving Towards):
- f = 240 Hz
- f' = 288 Hz
- Let v_sound = V
- 288 = 240 (V + v) / (V - v)
- 288/240 = (V + v) / (V - v)
- 6/5 = (V + v) / (V - v)
- 6(V - v) = 5(V + v)
- 6V - 6v = 5V + 5v
- V = 11v
- v = V/11
- Case 2 (Moving Away):
- f = 240 Hz
- f' = n Hz
- n = 240 (V - v) / (V + v)
- Substitute v = V/11:
- n = 240 (V - V/11) / (V + V/11)
- n = 240 (10V/11) / (12V/11)
- n = 240 (10/12)
- n = 240 (5/6)
- n = 40 * 5
- n = 200
Answer:
The value of n is 200Hz