Physics Test - ...

The energy required to break one bond in DNA is \(10^{-20} \mathrm{~J}\). This value in \(\mathrm{eV}\) is nearly:

A circular coil of radius \(R\) carries a current \(i\). The magnetic field at its center is \(B\). The distance from the center on the axis of the coil where the magnetic field will be \(\frac{B}{8}\) is:

The nuclear radius of a certain nucleus is \(7.2 \mathrm{fm}\) and it has a charge of \(1.28 \times 10^{-17} \mathrm{C}\). The number of neutrons inside the nucleus is:

Positive charge can be generated on a body by:

A liquid with coefficient of cubical expansion \(\gamma\) is contained in \(\alpha\) vessel having coefficient of linear expansion \(\frac{\gamma}{3}\). When heated, what will happen to the level of the liquid in the vessel?

In a photoelectric experiment ultraviolet light of wavelength \(280 \mathrm{~nm}\) is used with lithium cathode having work - function \(\phi=2.5 \mathrm{eV}\). If the wavelength of incident light is switched to \(400 \mathrm{~nm}\), find out the change in the stopping potential.

\(\left(\mathrm{h}=6.63 \times 10^{-34} \text { Js., and } \mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1}\right)\)

What are the components of nucleus of an atom?

Which one of the following has maximum inertia?

A car starting from rest is accelerated at a constant rate \(\alpha\) until it attains a speed \(v\). It is then retarded at a constant rate \(\beta\) until it comes to rest. The average speed of the car for its entire journey is:

A 2 meter long scale with least count of \(0.2 \mathrm{~cm}\) is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at \(80 \mathrm{~cm}\) mark and \(1 \mathrm{~m}\) mark. respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at \(180 \mathrm{~cm}\) mark. The \(\ \%\) error in the estimation of focal length is :