41.

Assertion:  The conductivity of an electrolyte is very low as compared to a metal at room temperature. 

Reason:  The number density of free ions in electrolyte is much smaller as compared to the number density of free electrons in metals. Further, ions drift much more slowly, being heavier.

• 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.

de-Broglie wavelength associated with a ball of mass 1 kg having kinetic energy 0.5 J is

• 6.63 × 10^-30 m

• 6.63 × 10^-34 m

• 1.32 × 10^-33 m

• 1.32 × 10^-34 m

Total energy of an electron in hydrogen atoms above 0 eV leads to

• ionisation of the atom

• accelerate the atom

• send the atom in higher excited state

• none of these

If the plate resistance oftriode valve is 13 x 10⁶ Ω and amplification factor is 21. The mutual conductance will be

• 1.6 × 10^-6 mho

• 1.6 × 10⁶ mho

• 2.6 × 10^-5 mho

• 2.6 × 10⁵ mho

A hemisphere is positively charged uniformly. The electric field at a point on a diameter away from the centre is directed

• perpendicular to the diameter

• parallel to the diameter

• at an angle tilted towards the diameter

• at an angle tilted away from the diameter

In a certain double slit experimental arrangement, interference fringes of width 1 mm each are observed when light of wavelength 5000 A^o  is used. Keeping the setup unaltered, if the source is replaced by another of wavelength 6000 A^o, the fringe width will be

• 1.2 mm

• 0.5 mm

• 1 mm

• 1.5 mm

The half-life of radium is 1600 years. What is the fraction of sample undecayed after 6400 years?

• $\frac{1}{16}$

• $\frac{1}{4}$

• $\frac{1}{8}$

• $\frac{1}{24}$

Mutual inductance of two coils can be increased by

• decreasing the number of turns in the coils

• increasing the number of turns in the coils

• winding the coils on wooden cores

• None of these

A person uses + 1.5 D glasses to have normal vision from 25 cm onwards. He uses a + 20 D lens as a simple microscope to see an object. What is the maximum magnifying power if he uses the microscope without glasses.

• 8

• 9

• 10

• 11

Ionisation potential of hydrogen atom is 13.6 V. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atoms according to Bohr's theory will be

• one

• two

• four

• three