Current Electricity — Physics STD 12 Science — Question

In the following atoms and moleculates for the transition from n = 2  to n = 1, the spectral line of minimum wavelength will be produced by

(a) Hydrogen atom

(b) Deuterium atom

(c) Uni-ionized helium

(d) di-ionized lithium

Which of the following is diamagnetism

(a) Aluminium

(b) Quartz

(c) Nickel

(d) Bismuth

Which of the following is not a correct statement

(a) Resistivity of electrolytes decreases on increasing temperature

(b) Resistance of mercury falls on decreasing its temperature

(c) When joined in series a 40 W bulb glows more than a 60 W bulb

(d) Resistance of 40 W bulb is less than the resistance of 60 W bulb

Let E, G and N represent the magnitudes of electromagnetic gravitational and nuclear forces between two electrons at a given separation. Then:

1. N > E > G
2. E > N > G
3. G > N > E
4. E > G > N

Wheatstones’s bridge cannot be used for measurement of very _______ resistances.

Crystal structure is studied by:

The energy of emitted photoelectrons depends upon :

The peak value of voltage of an A.C. circuit is 440 V. Its virtual voltage is :

If   and   are the electric and magnetic field vectors of E.M. waves then the direction of propagation of E.M. wave is along the direction of

(a)

(b)

(c)

(d) None of these

Two cells, e.m.f. of each is E and internal resistance r are connected in parallel between the resistance R. The maximum energy given to the resistor will be, only when

(a) R = r/2

(b) R = r

(c) R = 2r

(d)  R = 0