Moving Charges and Magnetism — Physics STD 12 Science — Question

The force with which a magnet attracts objects like iron is called ....................... .

In a charged capacitor, the energy is stored in:

A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The e.m.f. of the cell needed to make the bulb glow at full intensity is

(a) 4.5 V

(b) 1.5 V

(c) 2.67 V

(d) 13.5 V

Which of the following series of hydrogen spectrum is in visible range?

Magnetic moment of a thin bar magnet is M. If it is cut first perpendicular to length and then perpendicular to breadth, then magnetic moment of obtained piece is:

The condensers of capacity  and  are connected in parallel, then the equivalent capacitance is

(a)

(b)

(c)

(d)

A big drop is formed by mixing 64 small drops. If each small drop has charge Q, then the charge on the big drop will be

Magnetic induction is a

(a) Scalar quantity

(b) Vector quantity

(c) Both (a) and (b)

(d) None of the above

A radioactive material decays by simultaneous emission of two particles with respective half lives 1620 and 810 years. The time (in years) after which one- fourth of the material remains is

(a) 1080

(b) 2430

(c) 3240

(d) 4860

A magnet is placed in iron powder and then taken out, then maximum iron powder is at

(a) Some away from north pole	(b) Some away from south pole
(c) The middle of the magnet	(d) The end of the magnet