In figure shows three long straight wires $P, Q$ and $R$ carrying currents normal to the plane of the paper. All three currents have the same magnitude. Which arrow best shows the direction of the resultant force on the wire $P$

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If $\vec{E}$ and $\vec{B}$ represent the electric and magnetic fields respectively, then the region of space may have :

($A$) $\mathrm{E}=0, \mathrm{~B}=0$

($B$) $\mathrm{E}=0, \mathrm{~B} \neq 0$

($C$) $\mathrm{E} \neq 0, \mathrm{~B}=0$

($D$) $\mathrm{E} \neq 0, \mathrm{~B} \neq 0$

Choose the most appropriate answer from the options given below :

Define Ampere from two current carrying parallel wires.

A loop of irregular shape carrying current is located in an external magnetic field. If  wire is flexible it will take the shape of

A triangular shaped wire carrying $10 A$ current is placed in a uniform magnetic field of $0.5\,T$, as shown in figure. The magnetic force on segment $CD$ is $....N$ $($ Given $BC = CD = BD =5\,cm )$.

A winding wire which is used to frame a solenoid can bear a maximum $10\, A$ current. If length of solenoid is $80\,cm$ and it's cross sectional radius is $3\, cm$ then required length of winding wire is $(B = 0.2\,T)$