Two thin convex lenses of focal lengths 4 cm and 8 cm are separated by a distance of 4 cm in air. The combination will have the focal length
The combined focal length F of two convex lenses of focal lengths f1 and f2, separated by a distance d can be calculated by using the formula 1/F = 1/f1 + 1/f2 - d/f1.f2.
Two metallic wires A and B are of same material and have equal length. If the cross-sectional area of B is double that of A, then which one among the following is the electrical resistance of B?
The torque on a rectangular coil placed in a uniform magnetic field is large when the
The thermal conductivity of copper is 4 items that of brass. Two rods of copper and brass having same length and cross-section are joined end to end. The free end of copper is at 0o C and the free end of brass is at 100o C. The temperature of the junction is
If the focal length of the biconvex lens is 25 cms, then the power of the lens will be
A body attached to a spring balance weighs 10 kg on the Earth. The body attached to the same spring balance is taken to a planet where gravity is half that of the Earth. The balance will read