Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Four capacitors are connected as shown in the figure. Their capacities are indicated in the figure. The effective capacitance between points x  and y  is (in μF)

(a)

(b)

(c)

(d) 2

Two particles A and B of masses   and  respectively and having the same charge are moving in a plane. A uniform magnetic field exists perpendicular to this plane. The speeds of the particles are   and   respectively, and the trajectories are as shown in the figure. Then

(a)	(b)
(c)  and	(d)  and

Dimensions of permeability is :

The ionization potential for second He electron is

(a) 13.6 eV

(b) 27.2 eV

(c) 54.4 eV

(d) 100 eV

A paramagnetic material is kept in a magnetic field. The field is increased till the magnetization becomes constant. If the temperature is now decreased, the magnetization

1. Will increase.
2. Decrease.
3. Remain constant.
4. May increase or decrease.

The electric potential at a point (x, y) in the  x - y  plane is given by V = -kxy. The field intensity at a distance r from the origin varies as

(a)

(b) r

(c)

(d)

A 40 mF capacitor in a defibrillator is charged to 3000 V. The energy stored in the capacitor is sent through the patient during a pulse of duration 2ms. The power delivered to the patient is

(a) 45 kW

(b) 90 kW

(c) 180 kW

(d) 360 kW

The properties of a surface are different from those of the bulk liquid because the surface molecules:

1. Are smaller than other molecules.
2. Acquire charge due to collision from air molecules.
3. Find different type of molecules in their range of influence.
4. Feel a net force in one direction.

Two identical magnetic dipoles of magnetic moments 1.0 A-m² each, placed at a separation of 2m with their axis perpendicular to each other. The resultant magnetic field at a point midway between the dipoles is

(a) 5

(b)

(c)

(d) None of these

On increasing the temperature of a conductor, its resistance increases because -