If heat engine is filled at temperature 27$$^\circ$$C and heat of 100 k cal is taken from source at temperature 677$$^\circ$$C. Work done (in J) is
During $$\alpha$$-decay, atomic mass of parent nuclei is
A point object is placed on the optic axis of a convex lens of focal length $$f$$ at a distance of $$2f$$ to the left of it. The diameter of the lens is $$d$$. An eye is placed at a distance of $$3f$$ to the right of the lens and a distance $$h$$ below the optic axis. The maximum value of $$h$$ to see the image is
For CE transistor amplifier, the audio signal voltage across the collector resistance of 4 k$$\Omega$$ is 5 V. If the current amplification factor of the transistor is 100 and base resistance is 2 k$$\Omega$$, then input signal voltage is