Physics Ncert Solutions Class 12th

If ${\text{∮}\mathrm{}}_{\mathrm{s}}\vec{\mathrm{E}}\cdot \overrightarrow{\mathrm{d}\mathrm{S}}=0$  over a surface, then:

A galaxy is moving away from the earth at a speed 286 kms^-1. The shift in wavelength of a redline at 630 nm is x*10^-10 m. The value of x, to the nearest integer, is.
[Take the value of speed of light c, as 3*10⁸ ms^-1]

The typical output characteristics curve for a transistor working in the common-emitter configuration is shown in the figure.

The estimated current gain from the figure is.

The correct relation between α (ratio of collector current to emitter current) and β (ratio of collector current to base current) of a transistor is :

The circuit shown in the figure consists of a charged capacitor of capacity 3μF and a charge of 30μC. At time t = 0, when the key is closed, the value of current flowing through the 5MΩ resistor is 'x' μA. The value of 'x' to the nearest integer is---------.

A parallel plate capacitor has plate area 100m² and plate separation of 10m. The space between the plates is filled up to a thickness 5m with material of dielectric constant of 10. The resultant capacitance of the system is 'x' pF.
The value of ε? = 8.85 * 10?¹² F.m?¹
The value of 'x' to the nearest integer is ----------.

Match List-I with List-II

Choose the most appropriate answer from the options given below :

Two cells of emf 2E and E with internal resistance r? and r? respectively are connected in series to an external resistor R (see figure). The value of R, at which the potential difference across the terminals of the first cell becomes zero is:

A carrier signal C(t) = 25 sin(2.512 * 10¹⁰t) is amplitude modulated by a message signal m(t) = 5 sin(1.57 * 10⁸t) and transmitted through an antenna. What will be the bandwidth of the modulated signal?

Your friend is having eye sight problem. She is not able to see clearly a distant uniform window mesh and it appears to her non-uniform and distorted. The doctor diagnosed the problems as: