Physics Test 100

A parallel beam of monochromatic light is incident on a narrow rectangular slit of width 1 mm. When the diffraction pattern is seen on a screen placed at a distance of 2 m, the width of principal maxima is found to be 2.5 mm. The wavelength of light is

The figure shows the initial position of a point source of light s, a detector D and lens L. Now at t = 0, all three starts moving towards right with different velocity as shown in figure. The times at which detector receives the maximum light, is (Assume that the detector is initially just touching the lens).

Figure shows the anode potential vs photo-current graph when photons of 6 eV are incident on cathode in a photoelectric experiment set-up. In the same experimental set-up, if photons of 8 eV and same intensity are incident on cathode, then anode-potential vs photo-current graph will be (assume 100% efficiency of photons to eject photo-electrons in both cases)

A sound source is located somewhere along the x-axis. Experiment shows that the same wavefront simultaneously reaches listeners at x = –10m and x = +4.0 m. A third listener is positioned along the positive y-axis. What is y-coordinate (in m) if the same wavefront reaches at him at the same instant it does the first two listeners ?

The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is :

At t < 0, the capacitor is charged and the switch is opened. At t = 0 the switch is closed. The shortest time T at which the charge on the capacitor will be zero is given by :

In the circuit shown swith S is connected  to position 2 for a long time and then joined to position 1. The total heat produced in resistance R₁ is:

A solid cylinder attached to horizontal massless spring can roll without slipping along horizontal surface. Find time period of oscillation.

Assuming the sun to be a spherical body (e = 1) of radius R at a temperature of T K, evaluate the total radiant power, incident on Earth having radius r₀, at a distance r from the Sun, where r₀ is the radius of the earth and σ is Stefan's constant.

The minimum and maximum distance of a satellite from the centre of the earth are 2R and 4R, respectively, where R is the radius of earth and M is the mass of earth. The radius of curvature at the point of maximum distance is