Electric Charges and Fields — Physics STD 12 Science — Question

A long thin hollow metallic cylinder of radius 'R' has a current i ampere. The magnetic induction 'B'-away from the axis at a distance r from the axis varies as shown in

(a)

(b)

(c)

(d)

E.M.F. ofa cell is expressed in:

Which of these is a correct definition of electronic current?

By a monochromatic wave, we mean

(a) A single ray	(b) A single ray of a single colour
(c) Wave having a single wavelength	(d) Many rays of a single colour

The materials suitable for making electromagnets should have:

Which of the following is correct?

Choose the correct statement about the properties of magnetic lines of forces.

When the light source is moving away, the Doppler effect for light is known as:

At what distance from a convex lens of focal length 30 cm, an object should be placed so that the size of the image be 1/2 of the object

(a) 30 cm

(b) 60 cm

(c) 15 cm

(d) 90 cm

In the connections shown in the adjoining figure, the equivalent capacity between A  and  B will be

(a) 10.8 μF

(b) 69 μF

(c) 15 μF

(d) 10 μF