Moving Charges ...

A photon of energy E ejects a photoelectron from a metal surface whose work function is $$W_0.$$ If this electron enters into a uniform magnetic field of induction B in a direction perpendicular to the field and describes a circular path of radius r, then the radius r is given by (in the usual notation)

A magnetic dipole $$\overrightarrow {\rm{M}} {\rm{ = }}\left( {{\rm{A}}\widehat {\rm{i}}{\rm{ + B}}\widehat {\rm{j}}} \right){\rm{J/Wb}}$$ is placed in magnetic field. $$\overrightarrow {\rm{B}} {\rm{ = }}\left( {{\rm{C}}{{\rm{x}}^{\rm{2}}}\widehat {\rm{i}}{\rm{ + D}}{{\rm{y}}^{\rm{2}}}\widehat {\rm{j}}} \right)$$ Wb in XY plane at $$\overrightarrow {\rm{r}} {\rm{ = }}\left( {{\rm{E}}\widehat {\rm{i}}{\rm{ + F}}\widehat {\rm{j}}} \right){\rm{m}}$$. Then force experienced by the dipole is:

In an experiment, setup $$A$$ consists of two parallel wires which carry currents in opposite directions as shown in the figure. $$A$$ second setup $$B$$ is identical to setup $$A$$, except that there is a metal plate between the wires. 
Let $$F_A$$ and $$F_B$$ be the magnitude of the force between the two wires in setup $$A$$ and $$B$$, respectively, then which of the following condition is correct:

An electron emitted from a hot filament is accelerated through a potential difference of 2.88 kV and enters a region of a uniform magnetic field of $$0.\pi$$ at an angle of $$30^{o}$$ with the field. Take the mass of an electron $$9 \times 10^{-31}$$ kg. The trajectory of the electron is

An electron accelerated through a potential difference $$V$$ passes through a uniform transverse magnetic field and experiences a force $$F$$. If the accelerating potential is increased to $$2V$$, the electron in the same magnetic field will experience a force :

The magnetic field due to current flowing in a ling straight conductor is directly proportional to the current and inversely proportional to the distance of the point of observation from the conductor. What is this law known as?

An electron gun G emits electrons of energy $$2$$ keV travelling in the positive x-direction. The electrons are required to hit the spot S where GS$$=0.1$$m, and the line GS makes an angle $$60^o$$ with the x-axis, as shown. A uniform magnetic field B parallel to GS exists in the region outside the electron gun. Find the minimum value of B needed to make the electrons hit S.

Two thin, long parallel wires separated by a distance by a distance $$d$$ carry a current of $$iA$$ in the same direction. They will

An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?

Two charged particles M and N are projected with the same velocity in a uniform magnetic field as shown. Then, M and N, respectively, can be