Physics Ncert Solutions Class 12th

For VHF signal broadcasting. km² of maximum service area will be covered by an antenna tower of height 30m, if the receiving antenna is placed at ground. Let radius of the earth be 6400km. (Round off to the Nearest Integer) (Take π as 3.14)

The output of the given combination gates represents:

A particle of mass 200MeV/c² collides with a hydrogen atom at rest. Soon after the collision the particle comes to rest, and the atom recoils and goes to its first excited state. The initial kinetic energy of the particle (in eV) is N/4. The value of N is: (Given the mass of the hydrogen atom to be 1GeV/c²)

An electrical power line, having a total resistance of 2Ω, delivers 1 kW at 220 V. The efficiency of the transmission line is approximately:

Activities of three radioactive substances A, B and C are represented by the curves A, B and C in the figure. Then their half lives T₁(A): T₁(B): T₁(C) are in the ratio:

In a series LR circuit, power of 400 W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0.8 . In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the value of C as (n/3π) μF, then value of ' n ' is

The out put characteristics of a transistor is shown in the figure. When VCE is 10 V and Ic = 4.0 mA, then value of βac is

Two charged thin infinite plane sheets of uniform surface charge density σ+and σ−, where |σ+| > |σ−|, intersect at right angle. Which of the following best represents the electric field lines for this system.

A two point charges 4q and –q are fixed on the x-axis at x = −d/2 and x = d/2, respectively. If a third point charge ' q ' is taken from the origin to x = d along the semicircle as shown in the figure, the energy of the charge will: