A wire of length '$$l$$' and resistance $$100 \Omega$$ is divided into 10 equal parts. The first 5 parts are connected in series while the next 5 parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is:
A horizontal force $$10 \mathrm{~N}$$ is applied to a block $$A$$ as shown in figure. The mass of blocks $$A$$ and $$B$$ are $$2 \mathrm{~kg}$$ and 3 $$\mathrm{kg}$$ respectively. The blocks slide over a frictionless surface. The force exerted by block $$A$$ on block $$B$$ is :
A tightly wound 100 turns coil of radius $$10 \mathrm{~cm}$$ carries a current of $$7 \mathrm{~A}$$. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as $$4 \pi \times 10^{-7} \mathrm{SI}$$ units):
In an ideal transformer, the turns ratio is $$\frac{N_P}{N_S}=\frac{1}{2}$$. The ratio $$V_S: V_P$$ is equal to (the symbols carry their usual meaning) :