Physics 2nd Paper CQ-Barishal Board-2023

What is energy band?

Doping is helpful for electric conductivity-Explain it.

Calculate the current amplification factor of the $1^{x}$ transistor.

Which transistor is more suitable as a current amplifier? Explain it.

What is capacitance?

The quantity of charge in a body cannot be continuous.-Explain it.

Calculate the voltage difference between the point $\mathrm{A}$ and $B$ of the circuit.

The circuit is completed by removing $R_{5}$, what will be the change in main current? Explain mathematically.

What is closed system?

The changes of intemal energy in isothermal process becomes zero-Explain it.

Calculate the changes of entropy in isothermal expansion of the heat engine.

Is it possible that the efficiency of the heat engine be 1.5 times keeping the source temperature unchanged? Analyze mathematically.

What is decay constant?

Why 'NAND' is called universal gate?

How many times will be required to decay $85 \%$ of the molecule?

According to the stem, the observation is correct or not-Explain mathematically.

What is polarisation?

Why the central fringe is brighter than the other bright fringes of Young's double slit experiment?

Calculate the distance between the points $\mathrm{O}$ and $\mathrm{P}$.

If the experiment is done in water, analyse mathematically the changes of width of the fringe.