A copper rod $$A B$$ of length $$l$$ is rotated about end $$A$$ with a constant angular velocity $$\omega$$. The electric field at a distance $$x$$ from the axis of rotation is
Electric field due to infinite, straight uniformly charged wire varies with distance $$r$$ as
A $$2 \mathrm{~g}$$ object, located in a region of uniform electric field $$\mathrm{E}=\left(300 \mathrm{NC}^{-1}\right) \hat{\mathbf{i}}$$ carries a charge $$Q$$. The object released from rest at $$x=0$$, has a kinetic energy of $$0.12 \mathrm{~J}$$ at $$x=0.5 \mathrm{~m}$$. Then, $$Q$$ is
If a slab of insulating material (conceptual). $$4 \times 10^{-3} \mathrm{~m}$$ thick is introduced between the plates of a parallel plate capacitor, the separation between the plates has to be increased by $$3.5 \times 10^{-3} \mathrm{~m}$$ to restore the capacity to original value. The dielectric constant of the material will be