Q7 of 31 Page 1

Show that the radius of the orbit in hydrogen atom varies as n2, where n is the principal quantum number of the atom.

The radius of orbit in hydrogen atom:

------- (i)

Also,

So, ------- (ii)

Dividing (ii) by (i), we get;

So,

Graph showing the variation of current versus voltage for a material GaAs is shown in the figure. Identify the region of

(i) Negative resistance

(ii) Where Ohm’s law is obeyed.

A proton and an -particle have the same de-Broglie wavelength. Determine the ratio of

(i) Their accelerating potentials

(ii) Their speeds.

Distinguish between ‘intrinsic’ and ‘extrinsic’ semiconductors.

Use the mirror equation to show that an object placed between f and 2f of a concave mirror produces a real image beyond 2f.