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

Frictional force between solids operates even when they do not move with respect to each other. Do we have viscous force acting between two layers even if there is no relative motion?

Answer the following questions:
Magnetic field lines are always nearly normal to the surface of a ferromagnet at every point. (This fact is analogous to the static electric field lines being normal to the surface of a conductor at every point.) Why?

Answer carefully:
What meaning would you give to the capacitance of a single conductor?

Predict the polarity of the capacitor in the situation described below:

How two coils should be winded so that magnitude of induced electromotive force is maximum?

With what Hertz produced electro-magnetic waves?

A laser light is focused by a converging lens. Will there be a significant chromatic aberration?

Mention the two characteristic properties of the material suitable for making core of a transformer.

Mark the correct options.

1. The luminous efficiency of a monochromatic source is always greater than that of a white light source of same power.
2. The luminous efficiency of a monochromatic source of wavelength 555nm is always greater than that of a white light source of same power.
3. The illuminating power of a monochromatic source of wavelength 555nm is always greater than that of a white light source of same power.
4. The illuminating power of a monochromatic source is always greater than that of a white light source of same power.

An inductor and a resistor are joined in series with any ac source. What is the phase difference in the potential difference across their ends?