Class 12th

In the given nuclear reaction, the elements X is: ${}_{11}^{22}\mathrm{N}\mathrm{a}\to \mathrm{X}+{\mathrm{e}}^{+}+v$

In hydrogen spectrum, the shortest wavelength in the Balmer series is $\lambda$ . The shortest wavelength in the Bracket series is :

The work functions of Caesium (Cs), Potassium (K) and Sodium (Na) are $2.14\mathrm{e}\mathrm{V},2.30\mathrm{e}\mathrm{V}$ and $2.75\mathrm{e}\mathrm{V}$ respectively. If incident electromagnetic radiation has an incident energy of $2.20\mathrm{e}\mathrm{V}$ , which of these photosensitive surfaces may emit photoelectrons?

The minimum wavelength of X-rays produced by an electron accelerated through a potential difference of $\mathrm{V}$  volts is proportional to:

For Young's double slit experiment, two statements are given below:

Statement I: If screen is moved away from the plane of slits, angular separation of the fringes remains constant.

Statement II: If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases.

In the light of the above statements, choose the correct answer from the options given below:

Light travels a distance $x$ in time $t1$ in air and $10x$ in time $t2$  in another denser medium. What is the critical angle for this

In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of $2.0*{10}^{10}\mathrm{H}\mathrm{z}$ and amplitude $48{\mathrm{V}\mathrm{m}}^{-1}$ . Then the amplitude of oscillating magnetic field is:

(Speed of light in free space $=3*108{\mathrm{m}\mathrm{s}}^{-1}$  )

An ac source is connected to a capacitor $C$ . Due to decrease in its operating frequency:

Two hollow conducting spheres of radii $R_1$ $$ and $R_2\left(R_1>>R_2\right)$ $\left({}^{}\right)$ have equal charge. The potential would be:

A $12\mathrm{V},60\mathrm{W}$ lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of $220\mathrm{V}$ . Assuming the transformer to be ideal, what is the current in the primary winding?