Alternating Current — Physics STD 12 Science — Question

A non-planar loop of conducting wire carrying a current I is placed as shown in the figure. Each of the straight sections of the loop is of length 2a. The magnetic field due to this loop at the point P (a,0,a) points in the direction

(a)

(b)

(c)

(d)

The wavelength of light diminishes μ  times (μ = 1.33 for water) in a medium. A diver from inside water looks at an object whose natural colour is green. He sees the object as

(a) Green

(b) Blue

(c) Yellow

(d) Red

1 g of hydrogen is converted into 0.993 g of helium in a thermonuclear reaction. The energy released is

(a) 63

(b) 63

(c) 63

(d) 63

The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the centre of the magnet is

(a)

(b)

(c)

(d)

The purpose of cathode in cathode ray tube is ______:

A device which converts electrical energy into mechanical energy is

(a) Dynamo

(b) generator

(c) Electric motor

(d) Induction coil

The time taken by sunlight to cross a 5 mm thick glass plate (μ = 3/2) is

(a) 0.25

(b) 0.167

(c) 2.5

(d) 1.0

A point charge q is rotated along a circle in the electric field generated by another point charge Q. The work done by the electric field on the roatating charge in one complete revolution is:

The efficiency of transformer is very high because

(a) There is no moving part in a transformer	(b) It produces very high voltage
(c) It produces very low voltage	(d) None of the above

Which one is not the correct statement

(a) 1 volt × 1 coulomb = 1 joule	(b) 1 volt × 1 ampere = 1 joule/second
(c) 1 volt × 1 watt = 1 H.P.	(d) Watt-hour can be expressed in eV