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

The layered lens is made of two kinds of glass. A point source of light is placed on its principal axis. If the reflections from the boundaries between layers are ignored, the lens will form

If a glass rod is rubbed on silk cloth and then brought near the bits of paper it...... then.

If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is(a) 150 (b)  200 (c) 250 (d)  400 

The electrostatic force between the metal plates of an isolated parallel capacitor C having a charge Q and area A is:

A positively charged particle projected towards east is deflected towards north by a magnetic field. The field may be:

1. Towards west.
2. Towards south.
3. Upward.
4. Downward.

The time constant of an LR circuit represents the time in which the current in the circuit(a) Reaches a value equal to about 37% of its final value(b) Reaches a value equal to about 63% of its final value (c) Attains a constant value(d) Attains 50% of the constant value

A potentiometer can measure emf of a cell because :

Which of the following spectral series in hydrogen atom give spectral line of 4860 Å (a) Lyman(b) Balmer(c) Paschen(d) Brackett