51.

Light travels faster in air than that in glass .This is accordance with

• wave theory of light

• corpuscular theory of light

• Neither(a) nor(b)

• Both (a) and (b)

In Young's double slit experiment, light of wavelength 6000 A⁰ is used to produced fringes of width 0.8 mm at a distance of 2.5 m. If the whole appart is dropped in liquid of refractive index 1.6, then the fringe width will be

• 0.2mm

• 0.4mm

• 0.5mm

• 0.6mm

The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0$\times {10}^{-15}$m is

• 8$\times {10}^6 \mathrm{V}$

• 80V

• $9\times {10}^{5 }\mathrm{V}$

• 9V

 In forward biased if the p-n junctions diode is forward biased, then width of potential barrier in p-n junction diode

• remains constant

• increase

• decrease

• None of these

If the energy released in the fission of one nucleus is 3.2x10^-11J, then number of nuclei required per second in a power plant of 16 kW is

• $0.5\times {10}^{14}$

• $0.5\times {10}^{12}$

• $5\times {10}^{12}$

• $5\times {10}^{14}$

A light of wavelength 2000 A^o falls on a metallic surface of work function 5.01 eV then required potential difference to slope fastest photoelectron is (h = 6.62 x 10^-34J-s)

• 4.8V

• 3.6V

• 2.4V

• 1.2V

The enregy of a photon corresponding to the visible light maximum wavelength is nearly

• 7ev

• 3.2eV

• 1eV

• 1.6eV

If an electron has orbital angular momentum quantum number l =7 then it will have an orbital angular momentum equal to 

• $\sqrt{56}\left(\frac{\mathrm{h}}{2\mathrm{\pi }}\right)$

• $57\left(\frac{\mathrm{h}}{2\mathrm{\pi }}\right)$

• $42\left(\frac{\mathrm{h}}{2\mathrm{\pi }}\right)$

• $7\left(\frac{\mathrm{h}}{2\mathrm{\pi }}\right)$

The radius of electron second stationary orbit in Bohr's atom is R. The radius of third orbit will be

• 2.25R

• 3R

• R/3

• 9R

The slope of plate characteristic and mutual characteristic curves of a triode valve is 0.02 mA / V and 1 mA / V. The amplification factor of triode valve is

• $2\times {10}^8$

• 20

• 50

• 40