Nuclear fusion is common to the pair:

$A$ man fires a bullet standing between two cliffs. The first echo is heard after $3 \ s$ and the second echo is heard after $5 \ s$. If the velocity of sound is $330 \ m/s$,then the distance between the cliffs is .... $m$.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $A$: Size of $Bk^{3+}$ ion is less than $Np^{3+}$ ion.
Reason $R$: The above is a consequence of the actinoid contraction.
In the light of the above statements,choose the correct answer from the options given below:

If a $p-n$ junction is forward biased,then which of the following figures gives the correct direction of current inside the semiconductor?

$A$ mass $M \text{ kg}$ is suspended by a weightless string. The horizontal force required to hold the mass at $60^{\circ}$ with the vertical is

$A$ Wheatstone bridge is balanced. Find the ratio of electric power dissipated in $(P + Q)$ to $(R + S)$.