Photosynthetic bacteria have pigments in

The use of anti-histamine,adrenaline,and steroids quickly reduces the symptoms of:

An electron makes a transition from orbit $n = 4$ to the orbit $n = 2$ of the hydrogen atom. The wave number of the emitted radiation ($R =$ Rydberg's constant) will be

Where is the compound squamous epithelium found?

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers :
$(A)$ In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident light.
$(B)$ In gas-filled photoemissive cells,the velocity of photoelectrons depends on the wavelength of the incident radiation.

The output current versus time curve of a rectifier is shown in the figure. The average value of output current in this case is