Assertion:  The energy of charged particle moving in a uniform magnetic field does not change. 

Reason: Work done by magnetic field on the charge is zero

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

A  Ge specimen  is  doped with Al. The concentration of acceptor  atoms  is ∼ 10²¹ atoms/m³. Given that the intrinsic concentration of electron-hole pairs is 10¹⁹/m³,  the concentration of the specimen is

• 10¹⁷/m³

• 10¹⁵/m³

• 10⁴/m³

• 10²/m³

In Young's double slit experiment, the distance between two slits is made three times then the fridge width will become

• 9 times

• 1/9 times

• 3 times

• 1/3 times

A laser beam is used for carrying out surgery because, it

• is highly monochromatic

• is highly coherent

• is highly directional

• can be sharply focussed

45.

A coverging lens forms a real image I of an object on its principal axis. A rectangular slab of refractive index and thickness  x  is introduced between  l  and the lens, I will move

• towards the lens ( μ - 1 ) x

• towards the lens by $\left(1 - \frac{1}{\mathrm{\mu }}\right)$ x

• away from the lens by (μ - 1 ) x

• away from the lens by $\left(1 - \frac{1}{\mathrm{\mu }}\right)$ x

N₁ atoms of a radioactive element emit N₂ beta particles per second. The decay constant of the element is ( m s^-1 )

• N₁/N₂

• N₂/N₁

• N₁ ( ln2 )

• N₂ ( ln2 )

Which of the following is matched wrongly?

• Oil drop experiment  → Millikan

• Dual nature of light → de Broglie

• Uncertainty principle → Heisenberg

• None of these

The forbidden gap in the energy bands of sillicon is

• 2.6 eV

• 1.1 eV

• 0.1 eV

• 6 eV

When white light passes through a prism, the deviation is maximum for

• violet light

• green light

• red light

• yellow light

Which of the following gates correspond to the truth table given below?   

• NAND

• OR

• XOR

• NOR