Atoms — Physics STD 12 Science — Question

Pick out the temperature at which iron becomes paramagnetic?

Nuclear fission was discovered by

(a) Auto Hahn and F. strassmann	(b) Fermi
(c) Bethe	(d) Rutherford

When a charge of 3 coulombs is placed in a uniform electric field, it experiences a force of 3000 Newton. Within this field, potential difference between two points separated by a distance of 1 cm is

(a) 10 volts

(b) 90 volts

(c) 1000 volts

(d) 3000 volts

The pressure exerted by an electromagnetic wave of intensity I (watts/m²) on a nonreflecting surface is [c is the velocity of light]

(a) Ic

(b)

(c) I/c

(d)

In a streamline flow:

1. The speed of a particle always remains same.
2. The velocity of a particle always remains same.
3. The kinetic energies of all the particles arriving at a given point are the same.
4. The momenta of all the particles arriving at a given point are the same.

In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency 1rad/ s in a magnetic field B. The maximum value of emf generated in the coil is:

The magnetic field produced at the centre of current carrying circular coil is :

A constant current i is maintained in a solenoid. Which of the following quantities will increase if an iron rod is inserted in the soleniod along axis?

1. Magnetic field at the centre.
2. Mangetic flux linked with the solenoid.
3. Self-inductance of the solenoid.
4. Rate of Joule heating.

A capacitor with no dielectric is connected to a battery at t = 0. Consider a point A in the connecting wires and a point B in between the plates.

1. There is no current through A.
2. There is no current through B.
3. There is a current through A as long as the charging is not complete.
4. There is a current through B as long as the charging is not complete.

Two point white dots are 1mm apart on a black paper. They are viewed by eye of pupil of diameter 3mm. Approximately what is the maximum distance up to which these dots can be resolved by the eye.