Electrostatics — Physics STD 12 Science — Question

At the magnetic poles of the earth, a compass needle will be

When a distant object is viewed through an astronomical telescope, its image will be :

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

A thermo couple is formed by two metals X and Y metal X comes earlier to Y in Seebeck series. If temperature of hot junction increases beyond the temperature of inversion. Then direction of current in thermocouple will so(a) X to Y through cold junction(b) X to Y through hot junction(c) Y to X through cold junction(d) Both (b) and (c)

For television broadcasting, the frequency employed is normally(a) 30-300 MHz(b) 30-300 GHz(c) 30-300 KHz(d) 30-300 Hz

In the absence of other conductors, the surface charge density(a) Is proportional to the charge on the conductor and its surface area(b) Inversely proportional to the charge and directly proportional to the surface area(c) Directly proportional to the charge and inversely proportional to the surface area(d) Inversely proportional to the charge and the surface area

The maximum kinetic energy of a photo electron emitted from a metal is 1.8 eV . The value of stopping potential (cut-off voltage) will be :

Let p and E denote the linear momentum and energy of a photon. If the wavelength is decreased:

1. Both p and E increase.
2. P increases and E decreases.
3. P decreases and E increases.
4. Both p and E decrease.