Moving Charges and Magnetism — Physics STD 12 Science — Question

No. of magnetic lines of force present per unit volume is called.

A thin metal plate P is inserted half way between the plates of a parallel plate capacitor of capacitance C in such a way that it is parallel to the two plates. The capacitance now becomes

(a) C

(b) C/2

(c) 4C

(d) None of these

The half-life of radioactive Polonium (Po) is 138.6 days. For ten lakh Polonium atoms, the number of disintegrations in 24 hours is

(a) 2000

(b) 3000

(c) 4000

(d) 5000

In a PN-junction diode not connected to any circuit

(a) The potential is the same everywhere

(b) The P-type is a higher potential than the N-type side

(c) There is an electric field at the junction directed from the N- type side to the P- type side

(d) There is an electric field at the junction directed from the P-type side to the N-type side

Particles which can be added to the nucleus of an atom without changing its chemical properties are called:

Wave nature of light is verified by

(a) Interference

(b) Photoelectric effect

(c) Reflection

(d) Refraction

To maintain a steady current through the conductor, some external device must do work. What does the external device provide?

If a positive charge is taken from a region of lower potential to a region of higher potential, then the electrical potential energy:

The phenomenon by which stars recedes from each other is explained by:

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)