Physics Test - ...

How much positive and negative charge is there in a cup of water?

At what height above the surface of the earth does the weight of an object reduce by \(1 \%\). Given the radius of the earth is \(6400\).

Diameter of plano-convex lens is \(6 \mathrm{~cm}\) and thickness at the centre is \(3 \mathrm{~mm}\). If speed of light in material of lens is \(2 \times 10^{8} \mathrm{~m} / \mathrm{s}\), the focal length of the lens is:

If the kinetic energy of a body is increased nine times then the momentum of the body will be increased by:

The color code of a resistance is given below:

The values of resistance and tolerance, respectively,are

The solids which have the negative temperature coefficient of resistance are:

A square loop of side length \(\mathrm L\) carries a current which produces a magnetic field \(\mathrm B_0\) at the centre \((\mathrm O)\) of the loop. Now the square loop is folded into two parts with one halfbeing perpendicular to the other (see fig). Calculate the magnitude of magnetic field at the centre \(\mathrm O\).

A straight wire of length \(\mathrm L\) and radius \(\mathrm a\) has a current \(\mathrm I\). A particle of mass \(\mathrm m\) and charge \(\mathrm q\) approaches the wire moving at a velocity \(\mathrm v\) in a direction anti parallel to the current. The line of motion of the particle is at a distance \(\mathrm r\) from the axis of the wire. Assume that \(\mathrm r\) is slightly larger than \(\mathrm a\) so that the magnetic field seen by the particle is similar to that caused by a long wire. Neglect end effects and assume that speed of the particle is high so that it crosses the wire quickly and suffers a small deflection \(\theta\) in its path. Calculate \(\theta\).

Which one among the following waves are called waves of heat energy?

From the figure, what is β_ac when V_CE is 10V and I_c is 4 mA?