The emf of a cell having internal resistance $$1 \Omega$$ is balanced against a length of $$330 \mathrm{~cm}$$ on a potentiometer wire. When an external resistance of $$2 \Omega$$ is connected across the cell, the balancing length will be :
A $$1 \mathrm{~kg}$$ object strikes a wall with velocity $$1 \mathrm{~m} \mathrm{~s}^{-1}$$ at an angle of $$60^{\circ}$$ with the wall and reflects at the same angle. If it remains in contact with wall for $$0.1 \mathrm{~s}$$, then the force exerted on the wall is :
The angular momentum of an electron moving in an orbit of hydrogen atom is $$\mathrm{1.5\left(\frac{h}{\pi}\right)}$$. The energy in the same orbit is nearly.
A particle is executing uniform circular motion with velocity $$\vec{v}$$ and acceleration $$\vec{a}$$. Which of the following is true?