Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Electric field strength due to a point charge of 5μC  at a distance of 80 cm from the charge is

(a)  N/C

(b) 7N/C

(c)  5N/Cv

(d) 4N/C

A thick wire is stretched so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire

(a) 2 : 1

(b) 4 : 1

(c) 3 : 1

(d) 1 : 4

Assertion  :  In Young’s experiment, the fringe width for dark fringes is different from that for white fringes.

Reason      : In Young’s double slit experiment the fringes are performed with a source of white light, then only black and bright fringes are observed.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

The SI unit of electrical energy is ____________?

X-ray incident on a material:

1. Exerts a force on it.
2. Transfers energy to it.
3. Transfers momentum to it.
4. Transfers impulse to it.

36 cells, each of emf 4V are connected in series and kept in a box. The combination shows an emf of 88V on the outside. Calculate the number of cells reversed.

A neutron, a proton, an electron and an α−particle enter a region of uniform magnetic field with equal velocities. The magnetic field is perpendicular to the plane of paper and directed into it. The tracks of particles are labeled in the figure. The neutron follows the track:

A compass needle is placed in the gap of a parallel plate capacitor. The capacitor is connected to a battery through a resistance. The compass needle:

In an inelastic collision:

1. The initial kinetic energy is equal to the final kinetic energy.
2. The final kinetic energy is less than the initial kinetic energy.
3. The kinetic energy remains constant.
4. The kinetic energy first increases then decreases.

The charges on two sphere are +7mC and – 5mC respectively. They experience a force F. If each of them is given and additional charge of – 2mC, the new force of attraction will be

(a) F

(b) F / 2

(c) F/

(d) 2F