51.

What is the de-Broglie wavelength of the electron accelerated through a potential difference of 100 V ?

• $12.27 \stackrel{\circ }{\mathrm{A}}$

• $1.227 \stackrel{\circ }{\mathrm{A}}$

• $0.1227 \stackrel{\circ }{\mathrm{A}}$

• $0.001227 \stackrel{\circ }{\mathrm{A}}$

The maximum kinetic energy of the photoelectrons depends only on

• potential 

• frequency

• incident angle

• pressure

Which of the following spectral series of hydrogen atom is lying in visible range of electromagnetic wave ?

• Paschen series

• Pfund series

• Lymen series

• Balmer series

What is the energy of the electron revolving in third orbit expressed in eV ?

• 1.51 eV

• 3.4 eV

• 4.53 eV

• 4 eV

The relation between half-life (T) and decay constant (λ) is

• λT = 1

• $\mathrm{\lambda T} = \frac{1}{2}$

• $\mathrm{\lambda T} = {\log }_{\mathrm{e}}2$

• $\mathrm{\lambda } = \log 2\mathrm{T}$

A force between two protons is same as the force between proton and neutron. The nature of the force is

• weak nuclear force

• strong nuclear force

• electrical force

• gravitational force

In n-type semiconductor, electrons are majority charge carriers but it does not show any negative charge. The reason is

• electrons are stationary

• electrons neutralize with holes

• mobility of electrons is extremely small

• atom is electrically neutral

For the given digital circuit, write the truth table and identify the logic gate it represents

• OR gate

• NOR gate

• NAND gate

• AND gate

If α-current gain of a transistoris 0.98. What is the value of β-current gain of the transistor ?

• 0.49

• 49

• 4.9

• 5

A tuned amplifier circuit is used to generate a carrier frequency of 2 MHz for the amplitude modulation. The value of $\sqrt{\mathrm{LC}}$ is

• $\frac{1}{2\mathrm{\pi } \times {10}^6}$

• $\frac{1}{2 \times {10}^6}$

• $\frac{1}{3\mathrm{\pi } \times {10}^6}$

• $\frac{1}{4\mathrm{\pi } \times {10}^6}$