The resistance of platinum wire at $$0^{\circ} \mathrm{C}$$ is $$2 ~\Omega$$ and $$6.8 ~\Omega$$ at $$80^{\circ} \mathrm{C}$$. The temperature coefficient of resistance of the wire is :
An electric dipole is placed as shown in the figure.
The electric potential (in 102 V) at point P due to the dipole is ($$\in_0$$ = permittivity of free space and $$\frac{1}{4 \pi \epsilon_{0}}$$ = K) :
10 resistors, each of resistance $$\mathrm{R}$$ are connected in series to a battery of emf $$E$$ and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased $$n$$ times. The value of $$n$$ is :
A very long conducting wire is bent in a semi-circular shape from $$A$$ to $$B$$ as shown in figure. The magnetic field at point $$P$$ for steady current configuration is given by :