Electrostatics — Physics STD 12 Science — Question

A proton exerts a force on a proton which is:

1. Gravitational.
2. Electromagnetic.
3. Nuclear.
4. Weak.

Quantam nature of light is explained by which of the following phenomenon(a) Huygen wave theory(b) Photoelectric effect(c) Maxwell electromagnetic theory(d) de-Broglie theory

A solid that transmits light in visible region and has a very low melting point possesses(a) Metallic bonding(b) Ionic bonding(c) Covalent bonding(d) Vander Waal’s bonding

A hank of uninsulated wire consisting of seven and a half turns is stretched between two nails hammered into a board to which the ends of the wire are fixed. The resistance of the circuit between the nails is determined with the help of electrical measuring instruments. Determine the proportion in which the resistance will change if the wire is unwound so that the ends remain to be fixed to the nails.

Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is:

For a chosen non-zero value of voltage, there can be more than one value of current in:

Monica wanted to take photographs of a monument. But since the surrounding is filled with smoke, she is not able to take good photos. Which one of the following electromagnetic waves can be used in this situation to help Monica?

LEDs have the following advantages over conventional incandescent low power lamps: