Electric Charges and Fields — Physics STD 12 Science — Question

A parallel plate condenser is immersed in an oil of dielectric constant 2. The field between the plates is:

Nucleus of an atom whose atomic mass is 24 consists of:

The distance of closest approach of an alpha particle is d when it moves with a speed V towards a nucleus.
Another alpha particle is projected with higher energy such that the new distance of the closest approach is d/2. What is the speed of projection of the alpha particle in this case?

The equivalent capacitance in the circuit between A and B will be

(a) 1 μF

(b) 2 μF

(c) 3 μF

(d)

In the circuit shown here, at which point is the current least?

In a material medium, when a positron meets an electron both the particles annihilate leading to the emission of two gamma ray photons. This process forms the basis of an important diagnostic procedure called

(a) MRI

(b) PET

(c) CAT

(d) SPECT

Two non-ideal identical batteries are connected in parallel. Consider the following statements      

(i) The equivalent e.m.f. is smaller than either of the two e.m.f.s

(ii) The equivalent internal resistance is smaller than either of the two internal resistances

(a) Both (i) and (ii) are correct	(b) (i) is correct but (ii) is wrong
(c) (ii) is correct but (i) is wrong	(d) Both (i) and (ii) are wrong

A person uses spectacles of power +2D. He is suffering from

(a) Short sightedness or myopia	(b) Long sightedness or hypermetropia
(c) Presbyopia	(d) Astigmatism

Fraunhofer lines of the solar system is an example of

(a) Emission spectrum	(b) Emission band spectrum
(c) Continuous emission spectrum	(d) Line absorption spectrum