The condition for achieving laser action are (i) The system must be in a state of population inversion (ii) The excited state of the system should be in metastable state (iii) The atom should be in lower energy state (iv) No conditions required

What type of questions asked from the lesson of magnetic effect of electric current 

Wavelength of green light is

A) 400-450 nm

B) 500-550 nm

C) 660-720 nm

D) 720-800 nm

What is the difference between anaerobic & aerobic respiration? Name some organism that uses the aerobic mode of respiration?

What are the main components of our environment? Explain each of them briefly.

What are examples of hydrotropism plants?