Electric Charges and Fields — Physics STD 12 Science — Question

Equipotential surfaces:

In a laboratory experiment on emission from atomic hydrogen in a discharge tube, only a small number of lines are observed whereas a large number of lines are present in the hydrogen spectrum of a star. This is because in a laboratory:

1. The amount of hydrogen taken is much smaller than that present in the star.
2. The temperature of hydrogen is much smaller than that of the star.
3. The pressure of hydrogen is much smaller than that of the star.
4. The gravitational pull is much smaller than that in the star.

Unit of relative permeability is:

Consider a ray of light incident from air onto a slab of glass (refractive index n) of width d, at an angle θ. The phase difference between the ray reflected by the top surface of the glass and the bottom surface is:

In Young's double slit interference experiment, the slit separation is made 3 fold. The fringe width becomes

(a) 1/3 times

(b) 1/9 times

(c) 3 times

(d) 9 times

The angle of dip is the angle

(a) Between the vertical component of earth's magnetic field and magnetic meridian

(b) Between the vertical component of earth's magnetic field and geographical meridian

(c) Between the earth's magnetic field direction and horizontal direction

(d) Between the magnetic meridian and the geographical meridian

O₂ molecule consists of two oxygen atoms. In the molecule, nuclear force between the nuclei of the two atoms:

A solenoid (air core) ahs 400 turns, is 20cm long and has a cross section of 4cm². Then the coefficient of self induction is approximately

Two bulbs, one of 50 watt and another of 25 watt are connected in series to the mains. The ratio of the currents through them is

(a) 2 : 1	(b) 1 : 2
(c) 1 : 1	(d) Without voltage, cannot be calculated

If yellow light in the Young's double slit experiment is replaced by red light, the fringe width will

(a) Decrease	(b) Remain unaffected
(c) Increase	(d) First increase and then decrease