A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when :-

A particle starts from origin O from rest and moves with a uniform acceleration along the positive x-axis. Identify all figures that correctly represent the motion qualitatively. (a = acceleration, v = velocity, x = displacement, t = time)

A common emitter amplifier circuit, built using an npn transistor, is shown in the figure. Its dc current gain is 250, R_C = 1k$$\Omega$$ and V_CC = 10 V. What is the minimum base current for V_CE to reach saturation ?

The ratio of mass densities of nuclei of ⁴⁰Ca and ¹⁶O is close to :-