Physics Ncert Solutions Class 12th

In the figure, there is a conducting wire having current i and which has a shape of closed half ellipse $\left[\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\right]$  is kept in a uniform magnetic field B as shown. The magnitude of magnetic dipole moment of loop and torque acting on it are-

Which of the following transitions of He⁺ ion will give rise to spectral line which has same wavelength as some spectral line in hydrogen atom?

The electric field inside a sphere having charge density related to the distance from the centre as r (a is a constant) is:

Consider a p-n junction diode which has a potential drop of 0.5 V which is to be taken independent of current (under forward bias). If we want to use 1.5 V cell to forward bias the diode then what should be the value of resister (in Ω) used in series with the diode so that current may not exceed 10 mA, and hence may work safely.

A wave of frequency of 10 kHz and amplitude 20 volts is being used to modulate amplitude of carrier wave of frequency 1000 kHz and peak voltage 40 volts. Choose correct option regarding carrier modulated wave.

A common transistor ratio set requires 12V (D.C) for its operation. The D.C source is constructed by using a transformer and a rectifier circuit, which are operated at 220V (A.C) on standard domestic A.C, supply. The number of turns of secondary coil are 24, then the number of turns of primary are___________.

A resonance circuit having inductance and resistance 2 * 10^-4 H and 6.28 $\Omega$  respectively oscillates at 10 MHz frequency. The value of quality factor of this resonator is__________.

[p = 3.14]

An audio signal V_m = 20 sin 2p(1500t) amplitude modulates a carrier

V_C = 80 sin 2p (100,000t)( The value of percent modulation is______________.

If an emitter current is changed by 4mA, the collector current changes by 3.5mA. The value of b will be:

In the given, figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E. The transitions A, B and C respectively represents: