Alternating Current — Physics STD 12 Science — Question

A current of 16 ampere flows through molten NaCl for 10 minute. The amount of metallic sodium that appears at the negative electrode would be

(a) 0.23 gm

(b) 1.15 gm

(c) 2.3 gm

(d) 11.5 gm

For protecting a sensitive equipment from the external magnetic field, it should be

(a) Placed inside an aluminium cane

(b) Placed inside an iron cane

(c) Wrapped with insulation around it when passing current through it

(d) Surrounded with fine copper sheet

Unit of magnetic permeability is

(a) Amp/metre

(b) Amp/

(c) Henry

(d) Henry/metre

Li nucleus has three protons and four neutrons. Mass of lithium nucleus is 7.03.6005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect for lithium nucleus in amu is:

If the two ends of a p-n junction are joined by a wire:

In hydrogen atom, an electron is revolving in the orbit of radius 0.53  with 6.6  rotations/second. Magnetic field produced at the centre of the orbit is

(a) 0.125

(b) 1.25

(c) 12.5

(d) 125

If in a coil rate of change of area is 5 m²/milli second and current become 1 amp from 2 amp in 2  If magnitude of field is 1 tesla then self inductance of the coil is

(a) 2 H

(b) 5 H

(c) 20 H

(d) 10 H

Coulomb's Law is true for:

When a nucleus in an atom undergoes a radioactive decay, the electronic energy levels of the atom:

An electric bulb illuminates a plane surface. The intensity of illumination on the surface at a point 2m away from the bulb is 5  phot (lumen/cm²). The line joining the bulb to the point makes an angle of 60^o with the normal to the surface. The intensity of the bulb in candela is

(a) 40

(b) 40

(c) 20

(d) 40