Physics Test 23...

A block of mass 10 Kg is moving in x-direction with a constant speed of 10 m/sec. It is subjected to a retarding force F = –0.1 x joules/meter during its travel from x = 20 meters to x = 30 meters. Its final kinetic energy will be 

A string of length 0.4 m and mass 10^–2 kg is clamped at its ends. The tension in the string is 1.6 N. When a pulse travels along the string, the shape of the string is found to be the same at times t and t + Δt. The value of Δt is

A parallel combination of 0.1 MΩ resistor and a 10 μF capacitor is connected across a 1.5 V source of negligible resistance. The time (in seconds) required for the capacitor to get charged up to 0.75 V is approximately

A radioactive material has mean lives of 1620 years and 520 years for α and β emission respectively. The material decays by simultaneous α and β emission. The time in which 1/4th of the material remains intact is

In the circuit shown here, the point C is kept connected to point A till the current flowing through the circuit becomes constant. Afterward, suddenly, point C is disconnected from point A and connected to point B at time t = 0. Ratio of the voltage across resistance and the inductor at t = L/R will be equal to

In a modified form of Coulomb’s law let us write  where I₁ and I₂ are currents because of flowing charges q₁ and q₂. Then the dimensional formula for ε₀ is

A flat coil of area A and n turns in placed at the centre of a ring of radius r (r² >> A) and resistance R. The coil and the ring are co-planar. When the current in the coil increases from zero to i, the total charge circulating in the ring is

A converging lens of focal length f is placed just above a water surface, parallel to the surface, without touching it. A point source of light, S, is placed inside the water, vertically below the lens, at a depth f from it. This arrangement will produce.

A mass m is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, with what acceleration will the mass fall on release?

When electrons, accelerated through a potential difference pass through a medium containing electric field of intensity 20 V cm^–1 and magnetic field of intensity 1 T, these go undeviated. The velocity of the electrons is