V = $${{{V_0}} \over \pi }$$

$$ \Rightarrow $$ V = $$\left( {{{10} \over \pi }} \right)V$$

Barrier potential does not depend in diode design while barrier potential depends upon temperature, doping density and forward biasing.

In full wave rectifier the fundamental frequency in ripple is twice of input frequency.

When the collector is positive and emitter is negative with respect to base, it causes the forward biasing for each junction, which causes conduction of current.