Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

The power of convex lens of focal length 20 cm in dioptre is :

Resistance of the metal increases with temperature because:

Assertion : Short wave bands are used for transmission of radio waves to a large distance.
Reason    :  Short waves are reflected by ionosphere(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.

In the series combination of two or more than two resistances:

Light of wavelength 5000 Å falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be(a) 0.58 eV(b) 2.48 eV(c) 1.24 eV(d) 1.16 eV

If a coil of metal wire is kept stationary in a non-uniform magnetic field, then(a) An e.m.f. is induced in the coil(b) A current is induced in the coil(c) Neither e.m.f. nor current is induced(d) Both e.m.f. and current is induced

How will  the force between the two poles change if the two poles are connected by an iron rod keeping the distance between two magnetic poles constant ?

Lenz's law is associated with the principle of conservation of :

If there had been one eye of the man, then (a) Image of the object would have been inverted(b) Visible region would have decreased (c) Image would have not been seen three dimensional (d) (b) and (c) both