Electric Charges and Fields — Physics STD 12 Science — Question

A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

When a glass rod is rubbed with a silk cloth, charges appear on both. A similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law of conservation of charge.

Can we measure the potential difference across an unbiased p–n junction by connecting a sensitive voltmeter across it?

A glass contains some water at room temperature 20°C. Refrigerated water is added to it slowly. When the temperature of the glass reaches 10°C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5mm of mercury is 20°C and at 8.9mm of mercury it is 10°c.

Calculate the shortest wavelength in the Balmer series of hydrogen atom. In which region (infra-red, visible, ultraviolet) of hydrogen spectrum does this wavelength lie?

The minimum deviations suffered by red, yellow and violet beams passing through an equilateral transparent prism are 38.4°, 38.7° and 39.2° respectively. Calculate the dispersive power of the medium.

Write the definition of electric current and mention its types.

The earth revolves round the sun because the sun attracts the earth. The sun also attracts the moon and this force is 'about twice as large as the attraction of the earth on the moon. Why does the moon not revolve round the sun? Or does it?