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

Assertio : Hydrogen atom consists of only one electron but its emission spectrum has many lines.  
Reason  : Only Lyman series is found in the absorption spectrum of hydrogen atom whereas in the emission spectrum, all the series are found. (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 self inductance of a motor of an electric fan is 10H. In order to impart maximum power at 50Hz, it should be connected to a capacitance of:

The photoelectric effect can be understood on the basis of:

In which of the following the final image is erect?

The earth’s magnetic field always has a vertical component except at the:

The two metallic plates of radius r are placed at a distance d apart and its capacity is C. If a plate of radius r/2 and thickness d  of dielectric constant 6 is placed between the plates of the condenser, then its capacity will be(a) 7C/2(b) 3C/7(c) 7C/3(d) 9C/4

The most important features of superconductor is that:

Radioactive samples are stored in lead boxes because it is:

A conductor with a positive charge (a) Is always at +ve  potential(b) Is always at zero potential(c) Is always at negative potential(d) May be at +ve, zero or -ve potential

When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of:

1. Disperson of light.
2. Reflection of light.
3. Polarization of light.
4. Interference of light.