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

Find the wrong statement.

A P-type semiconductor has acceptor levels 57 meV above the valence band. The maximum wavelength of light required to create a hole is (Planck’s constant h = 6.6  J-s)

(a) 57

(b) 57

(c) 217100

(d) 11.61

The radius of the first (lowest) orbit of the hydrogen atom is  The radius of the second (next higher) orbit will be

(a) 4

(b) 6

(c) 8

(d) 10

The energy equivalent of 1 kilogram of matter is about

(a)  J

(b) 1 J

(c)  J

(d)  J

Assertion  :   Lenz’s law violates the principle of conservation of energy.

Reason      : Induced e.m.f., opposes always the change in magnetic flux responsible for its production.

(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 assertion is false but reason is true.

The specific charge of an electron is

(a) 1.6	(b) 4.8
(c) 1.76	(d) 1.76

Four charges are kept at the corner points of a square. The net force on a charge kept at the center of the square is _________?

Use of eddy currents is done in the following except

(a)  Moving coil galvanometer	(b)  Electric brakes
(c)  Induction motor	(d)  Dynamo

 Antiparticle of electron is

(a)

(b)

(c) Positron

(d) Neutrino

The de Broglie wavelength associated with a ball of mass 150g travelling at 30 ms⁻¹ is: