A $$240V$$ $$dc$$ shunt motor draws $$15A$$ while supplying the rated load at a speed of $$80$$ $$rad/s$$. The armature resistance is $$0.5$$ $$ohm$$ and the field winding resistance is $$80$$ $$ohm.$$

The external resistance to be added in the armature circuit to limit the armature current to $$125\% $$ of its rated value is

A capacitor consists of two metal plates each $$500 \times 500\,\,m{m^2}$$ and spaced $$6$$ $$mm$$ apart. The space between the metal plates is filled with a glass plate of $$4$$ $$mm$$ thickness and a layer of paper of $$2$$ $$mm$$ thickness. The relative permittivity of the glass and paper are $$8$$ and $$2$$ respectively. Neglecting the fringing effect, the capacitance will be (Given that $${\varepsilon _0} = 8.85 \times {10^{ - 12}}\,F/m$$ )

Two point charges $${Q_1} = 10\,\,\mu C$$ and $${Q_2} = 20\,\,\mu C$$ are placed at coordinates $$(1,1,0)$$ and $$\left( { - 1, - 1,0} \right)$$ respectively. The total electric flux passing through a plane $$z=20$$ will be

A coil of 300 turns is wound on a non-magnetic core having a mean circumference of 300 mm and a cross-sectional area of 300 mm². The inductance the coil corresponding to a magnetizing current of 3 A will be ( Given that $$\mu_0=4\mathrm\pi\times10^{-7}\;\mathrm H/\mathrm m$$)