The $$4^{\text {th }}$$ overtone of a closed organ pipe is same as that of $$3^{\text {rd }}$$ overtone of an open pipe. The ratio of the length of the closed pipe to the length of the open pipe is :
A long straight wire of length $$2 \mathrm{~m}$$ and mass $$250 \mathrm{~g}$$ is suspended horizontally in a uniform horizontal magnetic field of $$0.7 \mathrm{~T}$$. The amount of current flowing through the wire will be $$\left(\mathrm{g}=9.8 \mathrm{~ms}^{-2}\right)$$ :
According to Gauss law of electrostatics, electric flux through a closed surface depends on :
A ball is projected from point A with velocity $$20 \mathrm{~m} \mathrm{~s}^{-1}$$ at an angle $$60^{\circ}$$ to the horizontal direction. At the highest point $$\mathrm{B}$$ of the path (as shown in figure), the velocity $$\mathrm{v} \mathrm{m} \mathrm{s}^{-1}$$ of the ball will be: