Physics Test - ...

A passenger train moving at a speed of \(5\) ms^-1 is followed by an express train moving on the same track at a speed of \(30\) ms^-1. The rear side of the passenger train is at some distance. The driver of the express train applies brakes to avoid a collision. If the retardation due to brakes is \(4\) ms^-2, then find the time in which the accident is avoided after the application of brakes.

The kinetic energy of a body increases from 50 J to 150 J in 10 s. Then the power of the body is:

When the energy of the incident radiation is increased by \(20 \%\). The kinetic energy of the photoelectrons emitted from a metal surface increased from \(0.5 \mathrm{eV}\) to \(0.8 \mathrm{eV}\). The work function of the metal is:

When a real gas expands adiabatically against a finite pressure, its:

Two particles \(A\) and \(B\) move with constant velocities \(v _{1}\) and \(v _{2}\) along two mutually perpendicular straight lines towards the intersection point \(0\). At moment \(t=0\), the particles were located at distances \(l_{1}\) and \(l_{2}\) from \(0\), respectively. The shortest distance between \(A\) and \(B\) at some instant of time is:

In a potentiometer circuit, there is a cell of resistance \(5\;Ω\) and EMF \(2\; V\) connected to a uniform wire of length \(1000\; cm\) and resistance \(15\;Ω\). The potential gradient in the wire is:

A vessel contains two non-reacting gases Helium and Neon. The ratio of their partial pressure is 5 : 2. Find the ratio of the number of molecules of helium and Neon.

Resistances are connected in a meter bridge circuit as shown in the figure. The balancing length \(1_1\) is \(40 \mathrm{~cm}\). Now an unknown resistance \(\mathrm{x}\) is connected in series with \(\mathrm{P}\) and new balancing length is found to be \(80 \mathrm{~cm}\) measured from the same end. Then the value of \(x\) will be___________\(\Omega\).

Intensity at any point due to interference of two waves will be maximum, when path difference at that point is: