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

A wire has a resistance of 12 ohm. It is bent in the form of equilateral triangle. The effective resistance between any two corners of the triangle is

(a) 9 ohms

(b) 12 ohms

(c) 6 ohms

(d) 8/3 ohms

Assertion :   Charge is quantized

Reason    : Charge, which is less than 1 C is not possible

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

On passing electric current in two long straight conductors in mutually opposite directions, the magnetic force acting between them will be:

In the network of resistors shown in the adjoining figure, the equivalent resistance between A and B is

(a) 54 ohm

(b) 18 ohm

(c) 36 ohm

(d) 9 ohm

A new flashlight cell of e.m.f. 1.5 volts gives a current of 15 amps, when connected directly to an ammeter of resistance 0.04Ω. The internal resistance of cell is

(a) 0.04 Ω

(b) 0.06 Ω

(c) 0.10 Ω

(d) 10 Ω

With a change of load resistance of a triode, used as an amplifier, from 50 kilo ohms to 100 kilo ohms, its voltage amplification changes from 25 to 30. Plate resistance of the triode is

(a) 25 kW

(b) 75 kW

(c) 7.5 kW

(d) 2.5 kW

The combination of a convex lens (f = 18 cm) and a thin concave lens (f = 9 cm) is

(a) A concave lens (f = 18 cm)	(b) A convex lens (f = 18 cm)
(c) A convex lens (f = 6 cm)	(d) A concave lens (f = 6 cm)

The energy of a photon of a characteristic X-ray from a Coolidge tube comes from:

1. The kinetic energy of the striking electron.
2. The kinetic energy of the free electrons of the target.
3. The kinetic energy of the ions of the target.
4. An atomic transition in the target.

The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is .The average earth- sun distance is 1.5 . The mass lost by the sun per day is (1 day = 86400 seconds)

(a) 4.4

(b) 7.6

(c) 3.8

(d) 3.8

Van de Graaff generator is used to: