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

A circular disc is placed in front of a narrow source. When the point of observation is at a distance of 1 meter from the disc, then the disc covers first HPZ. The intensity at this point is I₀. The intensity at a point distance 25 cm from the disc will be

(a)

(b)

(c)

(d)

There are  n similar conductors each of resistance R. The resultant resistance comes out to be  x when connected in parallel. If they are connected in series, the resistance comes out to be

(a)

(b)

(c) x/n

(d) nx

An oscillator is producing FM waves of frequency 2 kHz with a variation of 10 kHz. What is the modulating index

(a) 0.20

(b) 5.0

(c) 0.67

(d) 1.5

A 1mm thick paper of dielectric constant 4 lies between the plates of a parallel-plate capacitor. It is charged to 100 volt the intensity of electric field between the plates of the condenser will be:

Choose the correct answer from the alternatives given.
Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor.

A dip circle is taken to geomagnetic equator. The needle is allowed to move in a vertical plane perpendicular to the magnetic meridian. The needle will stay:

In a cathode ray tube, what is the effect on the beam of particles if a hotter filament is used?

The unit of magnetic flux is

(a)

(b) Weber

(c) Henry

(d) Ampere/m

A biconvex lens of glass having refractive index 1.47 is immersed in a liquid. It becomes invisible and behaves as a plane glass plate. The refractive index of the liquid is :

Two long and parallel wires are at a distance of 0.1 m and a current of 5 A is flowing in each of these wires. The force per unit length due to these wires will be

(a) 5

(b) 5

(c) 2.5

(d) 2.5