A coil of 100 turns and area $$2 \times 10^{-2} \mathrm{~m}^2$$ is pivoted about a vertical diameter in a uniform magnetic field and carries a current of $$5 \mathrm{~A}$$. When the coil is held with its plane in North-South direction, it experiences a couple of $$0.33 \mathrm{~N}-\mathrm{m}$$. When the plane is East-West, the corresponding couple is $$0.4 \mathrm{~N}-\mathrm{m}$$. The value of magnetic induction is [Neglect earth's magnetic field]
A man stands between two parallel cliffs (not in middle). When he claps his hands, he hears two echoes one after is and the other after $$2 \mathrm{~s}$$. If the velocity of sound in air is $$330 \mathrm{~m} / \mathrm{s}$$, the width of the cliff is
Light of wavelength $$\lambda$$ strikes a photoelectric surface and electrons are ejected with kinetic energy $$K$$. If $$K$$ is to be increased to exactly twice its original value, the wavelength must be changed to $$\lambda^{\prime}$$, such that
When in $$p$$-$$n$$ junction diode, $$p$$ is connected to the positive terminal and $$n$$ is connected to the negative terminal, then it is