Wave Optics — Physics STD 12 Science — Question

Two resistors R and 2R are connected in series in an electric circuit. The thermal energy developed in R and 2R are in the ratio:

Three unequal resistors in parallel are equivalent to a resistance 1 ohm.  If two of them are in the ratio 1 : 2 and if no resistance value is fractional, the largest of the three resistances in ohms is

(a) 4

(b) 6

(c) 8

(d) 12

A wire has resistance 12 Ω. It is bent in the form of a circle. The effective resistance between the two points on any diameter is equal to

(a) 12 Ω

(b) 6 Ω

(c) 3 Ω

(d) 24 Ω

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

For a cell of e.m.f. 2V, a balance is obtained for 50 cm of the potentiometer wire. If the cell is shunted by a  2Ω resistor and the balance is obtained across 40 cm of the wire, then the internal resistance of the cell is

(a) 0.25 Ω

(b) 0.50 Ω

(c) 0.80 Ω

(d) 1.00 Ω

A cell of internal resistance 1.5Ω and of e.m.f. 1.5 volt balances 500 cm on a potentiometer wire. If a wire of 15 Ω  is connected between the balance point and the cell, then the balance point will shift

(a) To zero

(b) By 500 cm

(c) By 750 cm

(d) None of the above

NAND and NOR gates are called universal gates primarily because they:

The resistivity of iron is 1 . The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in ohm - m  will be

(a)

(b) 2

(c) 4

(d) 8

The amount of work done by the cell on a unit positive charge carrier to force it to go to the point of higher potential is called:

The current in a coil decreases from 1 A to 0.2 A. In 10sec. Calculate the coefficient of self inductance. If induced emf is 0.4 volt.

(a) 5 H

(b)  3 H

(c)  4 H

(d) 2 H