Atoms — Physics STD 12 Science — Question

Two light sources of intensities 8cd and 12cd are placed on the same side of a photometer screen at a distance of 40cm from it. Where should a 80cd source be placed to balance the illuminance?

How does the value of capacitance depend on the condition of the dielectric material when the space between the plates of a parallel plate capacitor is partially filled with a dielectric material?

How does the electric flux due to a point charge enclosed by a spherical Gaussian surface get affected when its radius is increased?

shows a capacitor made of two circular plates each of radius 12 cm, and separated by 5.0 cm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15A.

1. Calculate the capacitance and the rate of charge of potential difference between the plates.
2. Obtain the displacement current across the plates.
3. Is Kirchhoff’s first rule (junction rule) valid at each plate of the capacitor? Explain.

A light source emits monochromatic light of wavelength 555nm. The source consumes 100W of electric power and emits 35W of radiant flux. Calculate the overall luminous efficiency.

Two wires one of copper and other of manganin have same resistance and equal length. Which wire is thicker and why?

What is the luminous flux of a source emitting radio waves?

Does the charge given to a metallic sphere depend on whether it is hollow or solid? Give reason for your answer.

For what purpose are capacitors used in computers?