Atoms — Physics STD 12 Science — Question

A logic gate is an electronic circuit which

(a) Makes logic decisions

(b) Allows electrons flow only in one direction

(c) Works binary algebra

(d) Alternates between 0 and 1 values

The intensity of electric field required to balance a proton of mass 1.7   and charge 1.6   is nearly

(a)

(b) 1

(c) 1

(d) 1

If convex lens of focal length 80cm and a concave lens of focal length 50 cm are combined together, what will be their resulting power

(a) + 6.5 D

(b) – 6.5 D

(c) + 7.5 D

(d) – 0.75 D

The quantisation of charge indicates that:

In Bohr model of the hydrogen atom, the lowest orbit corresponds to

(a) Infinite energy	(b) The maximum energy
(c) The minimum energy	(d) Zero energy

A circular coil of radius 4 cm and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5 . The magnetic dipole moment of the coil is

(a) 0.15

(b) 0.3

(c) 0.45

(d) 0.6

What type of modulation is employed in India for radio transmission

(a) Amplitude modulation	(b) Frequency modulation
(c) Pulse modulation	(d) None of these

The resistance of a wire is 20 ohms. It is so stretched that the length becomes three times, then the new resistance of the wire will be

(a) 6.67 ohms

(b) 60.0 ohms

(c) 120 ohms

(d) 180.0 ohms

If the direction of the initial velocity of a charged particle is neither along nor perpendicular to that of the magnetic field, then the orbit will be:

Which device is used to produce electricity? Describe with a neat diagram.