One way in which the operation of a n-p-n transistor differs from that of a p-n-p

Two metal rods 1 and 2 of same lengths have same temperature difference between their ends. Their thermal conductivities are K₁ and K₂ and cross sectional areas A₁ and A₂, respectively. If the rate of heat conduction in 1 is four times that in 2, then

The displacement 'x' (in meter) of a particle of mass 'm' (in kg) moving in one dimension under the action of a force, is related to time 't' (in sec) by t = $$\sqrt x + 3$$. The displacement of the particle when its velocity is zero, will be

Vectors $$\overrightarrow A ,\overrightarrow B $$ and $$\overrightarrow C $$ are such that $$\overrightarrow A .\overrightarrow B = 0$$ and $$\overrightarrow A .\overrightarrow C = 0$$. Then the vector parallel to $$\overrightarrow A $$ is