The distance between the two plates of a parallel plate capacitor is doubled and the area of each plate is halved. If C is its initial capacitance, its final capacitance is equal to
A closely packed coil having 1000 turns has an average radius of 62.8 cm. If current carried by the wire of the coil is 1 A, the value of magnetic field produced at the centre of the coil will be (permeability of free space $$ = 4\pi \times {10^{ - 7}}$$ H/m) nearly
The magnetic field of a plane electromagnetic wave is given by $$\overrightarrow B = 3 \times {10^{ - 8}}\cos (1.6 \times {10^3}x + 48 \times {10^{10}}t)\widehat j$$, then the associated electric field will be :
The restoring force of a spring with a block attached to the free end of the spring is represented by