Direct impact between two smooth sphere mechanics

When an electric field is applied to the metal, the free electrons move in ______ direction

Choose all the options which are applications of static electricity.

• Photocopying

• Maglev Trains

• Electric Generators

• Pollution and smoke control from factories

• Painting cars to spread paint evenly

The following type of charging takes place without any physical contact being made.

• Charging by Induction

• Charging by Friction

• Charging by Conduction

• Charging by Convection

In QFET, Energy levels are

• discrete

• continuous

• discontinuous

• has increasing value

In solids, _________in outer most orbits of atoms determine its electrical properties

• protons

• neutron

• electrons

• positron

Two very small spheres have equal masses m, carry charges of the same sign and value q, and hang on strings of length L as shown in figure. Due to the repulsive force, the spheres are separated by some distance d. Find this distance. Assume that d << L so that you can use the approximation tan α ≈ sin α ≈ α

• 
  

  $\text{}\left(\frac{2Lq^2k}{mg}\right)^{\frac{1}{3}}$
  

• $\left(\frac{Lq^2k}{mg}\right)^{\frac{1}{3}}$

• $\sqrt{\frac{2Lq^2k}{mg}}$

• $\sqrt{\frac{Lq^2k}{mg}}$

Equipotentials at a great distance from a collection of charges whose total sum is not zero are approximately?

• spheres

• planes

• paraboloids

• ellipsoids

If the β (the fringe width) is 0.0156 cm and the distance between the contact edge and the fibre ’l’ in an airwedge is 4 cm, then what is the thickness of the fibre subjected in the experiment? (λ of sodium vapor lamp = 589.3 nm.)

• 750 nm

• 75 μm

• 82 μm

• 7.5 μm

According to this theory, free electrons move in a periodic potential provided by the lattice

• Classical free electron theory

• Quantum free electron theory

• free electron theory

• zone theory

If a unit positive charge is taken from one point to another over an equipotential surface then?

• Work is done on the charge.

• Work is done by the charge.

• Work done is constant.

• No work is done.