Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

PN-junction diode works as a insulator, if connected

(a) To A.C.

(b) In forward bias

(c) In reverse bias

(d) None of these

A small coil of N turns has area A and a current I flows through it. The magnetic dipole moment of this coil will be

(a) NI/A

(b)

(c)

(d) NIA

The order of magnitude of radius of nucleus is ___________.

If a charged particle kept at rest experiences an electromagnetic force:

If a spark is produced on removing the load from an AC circuit then the element connected in the circuit is.

Light owes its colour to its :

A 50 mH coil carries a current of 2 ampere. The energy stored in joules is

(a) 1

(b) 0.1

(c) 0.05

(d) 0.5

An ideal transformer has 100 turns in the primary and 250 turns in the secondary. The peak value of the ac is 28 V. The r.m.s. secondary voltage is nearest to

(a) 50 V

(b) 70 V

(c) 100 V

(d) 40 V

Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called

(a) Gamma camera	(b) CAT scan
(c) Radiotracer technique	(d) Gamma ray spectroscopy

A person's near point is 50 cm and his far point is 3 m. Power of the lenses he requires for

(i)  reading and  (ii) for seeing distant stars are

(a) – 2 D and 0.33 D

(b) 2 D and – 0.33 D

(c) – 2 D and 3 D

(d) 2 D and – 3 D