Nuclei — Physics STD 12 Science — Question

Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand

(a) None

(b) 1

(c) 2

(d) 3

An alpha particle moving with an initial velocity (uj)enters a region of uniform magnetic field B=Bk. the de-Broglie wavelength of the alpha particle.

A point source of electromagnetic radiation has an average power output of 800 W. The maximum value of electric field at a distance 4.0 m from the source is

(a) 64.7 V/m

(b) 57.8 V/m

(c) 56.72 V/m

(d) 54.77 V/m

A metallic particle having no net charge is placed near a finite metal plate carrying a positive charge. The electric force on the particle will be:

1. Towards the plate.
2. Away from the plate.
3. Parallel to the plate.
4. Zero.

An infinitely long, straight conductor AB is fixed and a current is passed through it. Another movable straight wire CD of finite length and carrying current is held perpendicular to it and released. Neglect weight of the wire

(a) The rod CD will move upwards parallel to itself

(b) The rod CD will move downward parallel to itself

(c) The rod CD will move upward and turn clockwise at the same time

(d) The rod CD will move upward and turn anti –clockwise at the same time

A current i ampere flows along the inner conductor of a coaxial cable and returns along the outer conductor of the cable, then the magnetic induction at any point outside the conductor at a distance r metre from the axis is

(a) ∞

(b) Zero

(c)

(d)

If L is the coherent length and c the velocity of light, the coherent time is:

A 500 Hz modulating voltage fed into an FM generator produces a frequency deviation of 2.25 kHz. If amplitude of the voltage is kept constant but frequency is raised to 6 kHz then the new deviation will be

(a) 4.5 kHz

(b) 54 kHz

(c) 27 kHz

(d) 15 kHz

The number of protons in an atom of atomic number Z and mass number A is: