Electric Charges and Fields — Physics STD 12 Science — Question

An a-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180^o. The nearest distance upto which a-particle reaches the nucleus will be of the order of

(a) 1 Å

(b)

(c)

(d)

The SI unit of capacitance is:

'Mirage' is a phenomenon due to

(a) Reflection of light	(b) Refraction of light
(c) Total internal reflection of light	(d) Diffraction of light

The oscillating electric and magnetic vectors of an electromagnetic wave are oriented along

The electrical conductivity of pure germanium can be increased by:

A square loop of side 5 cm enters a magnetic field with 1 cms^-1. The front edge enters the magnetic field at t = 0 then which graph best depicts emf

(a)	(b)
(c)	(d)

Which of the following of a radioactive material is a measure of its instability?

The impurity atom added to germanium to make it N-type semiconductor is

(a) Arsenic

(b) Iridium

(c) Aluminium

(d) Iodine

To produce magnified erect image of a far object, we will be required along with a convex lens, is

(a) Another convex lens

(b)  Concave lens

(c) A plane mirror

(d)  A concave mirror

The magnifying power of a microscope with an objective of 5 mm focal length is 400. The length of its tube is 20 cm. Then the focal length of the eye-piece is

(a) 200 cm

(b) 160 cm

(c) 2.5 cm

(d)  0.1 cm