PYQ Test: Modern Physics(12 Feb) - JEE MCQ

Emitter sends the majority charge carrriers towards the collector. Therefore emitter is most heavily doped.

β -rays are fast moving beam of electrons.

The resist ance of metal (like Cu) decr eases with decrease in temperature whereas the resistance of a semi-conductor (like Ge) increases with decrease in temperature.

The electromagnetic spectrum is as follows

∴ γ-rays has least wavelength

(c) : Linear momentum is conserved

When the temperature increases, certain boun ded electrons become free which tend to promote conductivity. Simultaneously  number of collisions between electrons and positive kernels increases

The number of  α - particles released = 8 Therefore the atomic number should decrease by 16
The number of β^- -particles released = 4
Therefore the atomic number should increase by 4.
Also the number of β⁺ particles released is 2, which should decrease the atomic number by 2.
Therefore the final atomic number is
92 –16 + 4 – 2 = 78

For one photocathode

For another photo cathode

Subtracting (ii) from (i) we get

The radioactive substances emit α -particles (Helium nucleus), β – particles (electrons) and neutrinoes.