When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated end is positive, the semiconductor is:

When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated end is positive, the semiconductor is: Correct Answer N-type

Explanation:

• On heating a semiconductor, equal number if holes/electron pair are generated, i.e. electrons and holes are generated in pairs.
• For an n-type semiconductor, initially the number of electrons are more. So the net number of electrons are greater than holes.
• ∴ When heated at one end, the concentration of electrons for an n-type semiconductor will increase at the edge than at the bulk of semiconductor.
• This will create a concentration gradient of electrons at the edge and at the bulk of semiconductor. This concentration gradient will result in excess electrons to move from the edge to the center, leaving behind positive charge.
• It is for this reason that the given semiconductor must be of n-type.

Note: If the semiconductor would have been a p-type, more holes would be created at the edge, which will result in the flow of holes from the edge to the center, leaving behind negative charge particle.