Ray Optics and Optical Instruments — Physics STD 12 Science — Question

A hemisphere shell is uniformly charged positively. The electric field at a point on a diameter away from the centre (inside the boundary of hemisphere shell) is directed:

In Bohr's model, the atomic radius of the first orbit is , then the radius of the third orbit is

(a)

(b)

(c)

(d)

If the ammeter in the given circuit reads 2 A, the resistance R is

(a) 1 ohm

(b) 2 ohm

(c) 3 ohm

(d) 4 ohm

A point positive charge is brought near an isolated conducting sphere. The electric field is best given by:

Pick out the wrong statement

(a) In a simple battery circuit, the point of lowest potential is the negative terminal of the battery

(b) The resistance of an incandescent lamp is greater when the lamp is switched off

(c) An ordinary 100 W lamp has less resistance than a 60 W lamp

(d) At constant voltage, the heat developed in a uniform wire varies inversely as the length of the wire used

As one considers orbits with higher values of n in a hydrogen atom, the electric potential energy of the atom:

1. Decreases.
2. Increases.
3. Remains the same.
4. Does not increase.

What is the unit of surface charge density in the SI unit?

Two infinite long wires, each carrying current I, are lying along x - axis and y - axis, respectively. A charged particle, having a charge q and mass m, is projected with a velocity u along the straight line OP. The path of the particle is (neglect gravity) a:

A convex lens has 9 cm focal length and a concave lens has – 18 cm focal length.  The focal length of the combination in contact will be

(a) 9 cm

(b) – 18 cm

(c) – 9 cm

(d) 18 cm

In a Young's double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be

(a) 0.30 mm

(b) 0.40 mm

(c) 0.53 mm

(d) 450 micron