Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

The concept of stationary orbits was proposed by

(a) Neil Bohr

(b) J.J. Thomson

(c) Ruther ford

(d) I. Newton

The avalanche breakdown in p-n junction is due to:

The Bohr model of atoms            

(a) Assumes that the angular momentum of electrons is quantized

(b) Uses Einstein’s photo-electric equation

(c) Predicts continuous emission spectra for atoms

(d) Predicts the same emission spectra for all types of atoms

A man having height 6 m. He observes image of 2 m height erect, then mirror used is

(a) Concave

(b) Convex

(c) Plane

(d) None of these

By corpuscular theory of light, the phenomenon which can be explained is

(a) Refraction

(b) Interference

(c) Diffraction

(d) Polarisation

Two identical conductors of copper and aluminium are placed in an identical electric fields. The magnitude of induced charge in the aluminium will be

(a) Zero	(b) Greater than in copper
(c) Equal to that in copper	(d) Less than in copper

A problem of practical interest is to make a beam of electrons turn at 90° corner. This can be done with the parallel plates shown in figure. An electron with kinetic energy 8.0 × 10^-17J enters through a small hole in the bottom plate. The strength of electric field that is needed if the electron is to emerge from an exit hole 1.0cm away from the entrance hole, traveling at right angles to its original direction is _______ ×10⁵N/ C.

A circular coil of 500 turns of wire has an enclosed area of  per turn. It is kept perpendicular to a magnetic field of induction 0.2 T and rotated by 180° about a diameter perpendicular to the field in 0.1 sec. How much charge will pass when the coil is connected to a galvanometer with a combined resistance of 50 ohms

(a) 0.2 C

(b) 0.4 C

(c) 2 C

(d) 4 C