RRB Technician Grade I 13 March 2026 Paper

Concept:In a p-type semiconductor, conductivity is directly proportional to the mobility of holes, which are the majority charge carriers.Explanation:The electrical conductivity of a p-type semiconductor is expressed as $\sigma = q(p\mu_p + n\mu_n)$.Here, $q$ is the charge, $p$ is the hole concentration, $\mu_p$ is the hole mobility, $n$ is the electron concentration, and $\mu_n$ is the electron mobility.In a p-type semiconductor, holes are the majority carriers, so the electron contribution is negligible.Therefore, the conductivity simplifies to $\sigma \approx q p \mu_p$.Since the other parameters, namely charge and hole concentration, are kept constant, conductivity depends only on hole mobility.Thus, $\sigma \propto \mu_p$.If the hole mobility is reduced to half its original value, then $\mu_p' = \frac{\mu_p}{2}$.Substituting this into the conductivity relation gives $\sigma' = q p \frac{\mu_p}{2} = \frac{\sigma}{2}$.Hence, the new conductivity becomes half of its original value.Answer:Reduced to half (Option C).