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In a semiconductor , electrical conductivity depends on the number of free charge carriers (electrons and holes). As temperature rises, thermal energy increases , which causes more covalent bonds to break , liberating more electrons into the conduction band and creating holes in the valence band. This increase in intrinsic carrier concentration enhances conductivity. The band gap does decrease slightly with temperature, but not drastically enough to be the primary cause. The dominant mechanism is the thermal excitation of electrons across the band gap due to breaking of covalent bonds.
A 150-metre train takes 6 seconds to cross a pole. If the same train takes 12 seconds to cross train 'C' that is travelling in opposite direction at 20 ...
A goods train leaves a station at a certain time and at a fixed speed. After 9 hours, an express train leaves the same station and moves in the same dir...
Two trains 165 metres and 135 metres in length are running towards each other on parallel tracks, one at the rate 70 km/hr and another at 38 km/hr. In h...
Train ‘A’ running with a speed of 108 km/hr crosses a vertical pole in 12 seconds. Find the approx. time taken by the train ‘A’ to cross a train...
A train takes 18 seconds to cross a 120-metre-long platform. If the speed of the train is 36 km/h, then find the time taken by the train to cross a 240-...
Train P takes 27 seconds to cross a tree, and Train Q overtakes Train P, both traveling in the same direction, in 3 minutes. The ...
Train ‘A’ travelling with a speed of 84 km/h can cross a pole in 12 seconds. If the length of train ‘B’ is 20% less than that of train ‘A’ a...
A train crosses a pilar in 20 seconds and a platform of length 300 metres in 25 seconds,then what will the 120% of the length of the train.
A train 200 metre long takes 30 sec to cross a man running at a speed of 4 km/hr in the direction opposite to that of train. What is the speed of the tr...
A train 200 m long running at 36 km/hr takes 45 seconds to cross a bridge. The length of the bridge is