Electricity and Magnetism Answers

Three point charges, q1, q2, and q3, are located at the vertices of an equilateral triangle. If q1 = q2, what value must q3 have so that the total potential energy of the arrangement is zero?

Two positive charges, each of 4.8 µC, and negative charge -6.36 µC are fixed at the vertices of an equilateral triangle of side 13 cm. Find the electrical force on negative charge.

An infinite long wire lying along the Y-axis is carrying a current 'i' . The magnetic flux through a circular loop of radius R in the XY-plane is
Ans. µiR

What is the decay constant?

A circular coil consists 70 closely wound turns and has a radius of 10cm. An externally produced magnetic field of magnitude 2×10^(-3)T is applied perpendicular to the coil.The net flux through the coil is found to vanish when the current in the coil is 2.2A. The inductance of the coil is
Ans 3mH

Two point charges of unknown magnitude and sign are placed
a distance d apart. (a) If it is possible to have E= 0 at any
point not between the charges but on the line joining them,
what are the necessary conditions and where is the point located(b) Is it possible, for any arrangement of two points charges, to find two points (neither at infinity) at which E=0 if so under what conditions?

The Apple states in the Accessory Design Guidelines that with new iPhone 12 models can be used MagSafe magnet accessories. The magnets in those shall be N48H NdFeB with a 7 μm - 13 μm NiCuNi plating finish (or similar) and shall meet the requirements in Table 23-7 (page 90).
Also in the guidelines states that any other magnets accept MagSafe shall be used with iPhones. The question is, how magnet from other materials, like N52H NdFeB can influence on the iPhone, if it will be constantly used in the accessories to iPhone?