$A$ black body radiates energy at the rate of $E \text{ W/m}^2$ at a high temperature $T \text{ K}$. When the temperature is reduced to $\left(\frac{T}{2}\right) \text{ K}$,the radiant energy is

What is the quantity of electricity (in Coulombs) required to deposit all the silver from $250 \ mL$ of $1 \ M \ AgNO_3$ solution?

Consider telecommunication through optical fibres. Which of the following statements is $NOT$ true?

Considering only the principal values of inverse functions,the set $A = \{x \geq 0 : \tan^{-1}(2x) + \tan^{-1}(3x) = \frac{\pi}{4}\}$

The plane faces of two identical plano-convex lenses,each having a focal length of $40 \, cm$,are placed against each other to form a biconvex lens. The distance from this lens at which an object must be placed to obtain a real,inverted image with magnification $-1$ is ...... $cm$.