Physics 2nd Paper CQ-Jessore Board-2019

What is called length contraction?

The velocity of a body cannot be more than the velocity of light by the theory of relativity - Explain it.

What is the threshold requency of the metal B?

Give your opinion with mathematial analaysis 3 photo-electric effect will occur on both $A$ and $B$ whether the stimulus.

Define semiconductor.

Why conductivity of a semiconductor increases due to doping?

What time will the atom take to become one-fifth of the initial amount if the decay constant of the radioactive substance is $4.02 \times 10^{-4} \mathrm{~J}^{-1}$ in the stem?

In the stem, after the time equal to the mean life time of the radioactive substance, the amount of unchanged atom is on the point $B$ in the graph-Explain.

Define Supernova.

The sun never becomes a black hole-Explain.

Determine the current gain of the circuit.

AC the device in the stem amplify the amplitude of the signal of - Analyse it.

Write down the zeroth law of thermodynamics.

Adiabatic process is an isoentropy process - Explain.

Calculate the electric potential at point $P$.

Will the magnitude of electric intensity at point $P$ is zero? Represent your logic with mathematical analysis.

Write down the definition of coefficient of self induction.

Why the apparent value of e.m.f is more important than the average value of e.m.f for $A C$ ?

What is the magnitude of torque applied on the coil in figure- 1 ?

If the torque remain same in both figure then what is the no. of turns change is needed in figure-2. Show by mathematical analysis.