Current Electricity — Physics STD 12 Science — Question

Same current i = 2A is flowing in a wire frame as shown in figure. The frame is a combination of two equilateral triangles ACD and CDE of side 1m. It is placed in uniform magnetic field B = 4T acting perpendicular to the plane of frame. The magnitude of magnetic force acting on the frame is

(a) 24 N

(b) Zero

(c) 16 N

(d)  8 N

Pick out the longest wavelength from the following types of radiations

(a) Blue light

(b) g-rays

(c) X-rays

(d) Red light

Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54Å. The value of the lattice constant for this lattice is

(a) 1.27 Å

(b) 5.08 Å

(c) 2.54 Å

(d) 3.59 Å

Two ions having masses in the ratio 1 : 1 and charges 1 : 2 are projected into uniform magnetic field perpendicular to the field with speeds in the ratio 2 : 3. The ratio of the radii of circular paths along which the two particles move is

(a) 4 : 3

(b) 2 : 3

(c) 3 : 1

(d) 1 : 4

Donor type impurity is found in

(a) Trivalent elements	(b) Pentavalent elements
(c) In both the above	(d) None of these

In L-R circuit, for the case of increasing current, the magnitude of current can be calculated by using the formula

(a)

(b)

(c)

(d)

A straight wire carrying a current 10 A is bent into a semicircular arc of radius 5 cm. The magnitude of magnetic field at the center is

(a) 1.5

(b) 3.14

(c) 6.28

(d)  19.6

A horizontal circular loop carries a current that looks clockwise when viewed from above. It is replaced by an equivalent magnetic dipole consisting of a south pole S and a north pole N:

1. The line SN should be along a diameter of the loop.
2. The line SN should be perpendicular to the plane of the loop.
3. The south pole should be slow the loop.
4. The north pole should be below the loop.

A hollow tube is carrying an electric current along its length distributed uniformly over its surface. The magnetic field:

The value of angle of dip is zero at the magnetic equator because on it

(a) V and H are equal	(b) The value of V and H is zero
(c) The value of V is zero	(d) The value of H is zero