After two hours, 1/16 of the initial amount of a certain radioactive isotope remains undecayed. What is the half-life of the isotope?

If a full-wave rectifier circuit is operating from 50 Hz mains, then the fundamental frequency in the ripple will be

A man of height 'h' walks along a straight path towards a lamp post of height H with a uniform velocity 'u'. The velocity of the edge of the shadow on the ground will be

Dimensions of resistance in an electrical circuit, in terms of dimensions of mass M, length L, time T and current l, would be

 In an LR circuit of 3 mH inductance and 4 resistance, an emf E = 4 cos 1000 t volt is applied. The current amplitude is

Two thin equiconvex lenses, each of focal length 0.2 m, are placed coaxially with their optic centres 0.5 m apart. What is the focal length of the combination?

In a Fresnel biprism experiment, the two positions of lens give separation between the slits as 16 cm and 9 cm. What is the actual distance of separation?

In a flywheel, mass is concentrated at the

If a carrier wave of 1 kHz is used to a carry signal, the wavelength of transmitting signal is

The magnetic field of Earth at a given point is 0.5 × 10^-5 Wb/m². This field is to be neutralised by magnetic induction at the centre of a circular conducting loop of radius 5.0 cm. The current required to be passed through the loop is nearly