Moving Charges and Magnetism — Physics STD 12 Science — Question

A parallel plate capacitor consists of two circular plates each of radius 12cm and separated by 5.0mm. The capacitor is being charged by an external source. The charging current is constant and is equal to 0.15A.The displacement current is:

In a region of constant potential:

An object is placed at a distance of 20 cm from a convex lens of focal length 10 cm. The image is formed on the other side of the lens at a distance (a) 20 cm (b) 10 cm(c) 40 cm (d) 30 cm

In any Bohr orbit of the hydrogen atom, the ratio of kinetic energy to potential energy of the electron is(a) 1/2(b) 2(c) -1/2   (d)  -2

The potential gradient at which the dielectric of a condenser just gets punctured is called(a) Dielectric constant(b) Dielectric strength(c) Dielectric resistance(d) Dielectric number

The photoelectric effect can be understood on the basis of:

In a triode valve (a) If the grid voltage is zero then plate current will be zero(b) If the temperature of filament is doubled, then the thermionic current will also be doubled(c) If the temperature of filament is doubled, then the thermionic current will nearly be four times(d) At a definite grid voltage the plate current varies with plate voltage according to Ohm’s law

Assertion  :   An aircraft flies along the meridian, the potential at the ends of its wings will be the same.
Reason     : Whenever there is change in the magnetic flux e.m.f. induces.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

The temperature of cold junction and neutral temperature of a thermocouple are  15℃ and 280℃  respectively. The temperature of inversion is(a) 295℃(b) 265℃(c) 545℃ (d) 575℃