Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A proton of mass m and charge +e is moving in a circular orbit in a magnetic field with energy 1 MeV. What should be the energy of α -  particle (mass = 4m and charge = + 2e), so that it can revolve in the path of same radius

(a) 1 MeV

(b) 4 MeV

(c) 2 MeV

(d) 0.5 MeV

Which of the following is not a unit of magnetic induction?

The condition for observing Fraunhofer diffraction from a single slit is that the light wavefront incident on the slit should be

(a) Spherical

(b) Cylindrical

(c) Plane

(d) Elliptical

A tank is filled with benzene to a height of 120 mm. The apparent depth of a needle lying at a bottom of the tank is measured by a microscope to be 80 mm.  The refractive index of benzene is

(a) 1.5

(b) 2.5

(c) 3.5

(d) 4.5

A group of N cells whose emf varies directly with the internal resistance as per the equation E_N = 1.5 r_N are connected as shown in the figure below.  The current I in the circuit is

(a) 0.51 amp

(b) 5.1 amp

(c) 0.15 amp

(d) 1.5 amp

The electric potential at a point (x, y) in the  x - y  plane is given by V = -kxy. The field intensity at a distance r from the origin varies as

(a)

(b) r

(c)

(d)

An elastic circular wire of length l carries a current I. It is placed in a uniform magnetic field   (Out of paper) such that its plane is perpendicular to the direction of . The wire will experience

(a) No force	(b) A stretching force
(c) A compressive force	(d) A torque

...X... is a machine that can build up high voltages of the order of a few million volts. Here, A refers to:

The motion of electron inside the conductor is :

Convex lens is used in :