51.

The relation between amplification factor (μ), plate resistance (r_p) and mutual conductance (g_m) of a triode value is given by :

• $\mathrm{\mu } = {\mathrm{r}}_{\mathrm{p}} \times {\mathrm{g}}_{\mathrm{m}}$

• ${\mathrm{r}}_{\mathrm{p}} = \mathrm{\mu } \times {\mathrm{g}}_{\mathrm{m}}$

• ${\mathrm{g}}_{\mathrm{m}} = \mathrm{\mu } \times {\mathrm{r}}_{\mathrm{p}}$

• none of these

A light of wavelength 5000 Å falls on a sensitive plate with photoelectric work function 1.90 eV. The kinetic energy of the emitted photoelectrons will be :

(Given, h = 6.62 × 10^-34 Joule second)

• 0.1 eV

• 2 eV

• 0.581 eV

• 1.581

Continuous emission spectrum, emitted wavelength about spectrum, the range depends upon:

• temperature of the source

• material of the source

• surface area of the source

• all of the above

The emission electron is possible by

• photoelectric effect

• thermionic effect

• both (a) and (b)

• none of the above

An electron and a proton are possessing the same amount of kinetic energies. The de-Broglie wavelength is greater for :

• electron

• proton

• both same

• none of these

In a mean life of radioactive sample :

• about $\frac{1}{3}$ of substance disintegrates

• about  $\frac{2}{3}$ of substance disintegrates

• about 90% of the substance disintegrates

• almost all the substance disintegrates

If the half-life of any sample of a radioactive substance is 4 days, then the fraction of the sample will remain undecayed after 2 days, will be

• $\sqrt{2}$

• $\frac{1}{\sqrt{2}}$

• $\frac{\sqrt{2} - 1}{\sqrt{2}}$

• $\frac{1}{2}$

On applying a reverse bias to a junction diode, it:

• lowers the potential barrier

• raises the potential barrier

• increases the majority carrier current

• increases the minority carrier current

A n-type semiconductor is

• negatively charged

• positively charged

• neutral

• none of the above

For the stability of any nucleus:

• binding energy per nucleon will be more

• binding energy per nucleon will be less

• no. of electrons will be more

• none of these