Task 2.1
At the tops of a square with a side of 0.1 m there are identical charges of the same name. The potential of the field created by them in the center of the square is 500 V. Determine the charge.

PROBLEM 2.11
Dust weighing 8 • 10-15 kg is kept in equilibrium between horizontally arranged plates of a flat capacitor. The potential difference between the plates is 490 V, and the gap between them is 1 cm. Determine how many times the charge of a dust particle is greater than an elementary one.

PROBLEM 2.21
The capacitor with a paraffin insulator is charged to a potential difference of 150 V. The field strength is 6 • 106 V / m, the area of ​​the plates is 6 cm2. Determine the capacitance of the capacitor and the surface charge density on the plates.

Task 2.31
The current density in a nickel conductor 25 m long is 1 MA / m2. Determine the potential difference at the ends of the conductor.

Task 2.41
Two infinitely long rectilinear conductors with currents of 6 and 8 A are perpendicular to each other. Determine the induction and intensity of the magnetic field in the middle of the shortest distance between the conductors, equal to 20 cm.

PROBLEM 2.51
An unbonded conductor weighing 0.1 g and a length of 7.6 cm is in equilibrium in a horizontal magnetic field of intensity 10 A / m. Determine the current in the conductor if it is perpendicular to the field induction lines.

Task 2.61
Perpendicular to the lines of induction of a homogeneous magnetic field by induction of 0.3 T, a conductor 15 cm long runs at a velocity of 10 m / s perpendicular to the conductor. Determine the EMF induced in the conductor.

Task 2.71
What is the volume density of energy of the magnetic field in a solenoid without a core, which has a dense single-layer winding with a wire of 0.2 mm in diameter, if a current of magnitude 0.1 A flows through it?