Physics Test 100

A mass m is placed at point P lies on the axis of a ring of mass M and radius R at a distance R from its center. The gravitational force on mass 'm' is :-

The acceleration due to gravity at the poles and the equator are g_p and g_e respectively. If the earth is a sphere of radius R_e and rotation about its axis with angular speed ω, then g_p – g_e is given by :-

The photoelectric threshold wavelength of a certain metal is 3000 Å. If the radiation of 2000 Å is incident on metal :

An electron of mass m_e and a proton of mass m_p are accelerated through the same potential difference. The ratio of the de-Broglie wavelength associated with an electron to that associated with proton is :

We wish to see inside an atom. Assuming the atom to have a diameter of 10 pm this means that one must be able to resolve a width of 10 pm. If an electron microscope is used, the minimum electron energy required is about :

If a photocell is illuminated with a radiation of 1240 Å, the stopping potential is found to be 8 volt; then the work function of emitter and the threshold wavelength are :

The ratio of de-Broglie wavelength of molecules of hydrogen and helium in two separate jars at temperatures of 27°C and 127°C respectively is :

The ratio of de-Broglie wavelength of α-particle to that of a proton being subjected to the same magnetic field so that the radii of their paths are equal to each other. Assuming the field induction vector  is perpendicular in the velocity vectors of the α-particle and the proton is :

An element A decays into an element C by a two step process :

One milliwatt of light of wavelength 4560 Å is incident on a caesium surface of work function 1.9 eV. Given that quantum efficiency of photoelectric emission is 0.5% planck constant h = 6.62 × 10^–34 J.sec velocity of light c = 3 × 10⁸ m/s, the photoelectric current liberated is :