CBSE
Multiple Choice QuestionsA coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a permanent magnet such that B is in plane of the coil. If due to current i in the triangle a torque T acts on it, the side l of the triangle is
An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B at the centre of the circle. The radius of the circle is proportional, to
B/v
v/B
√v/B
√B/v
In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant the ratio will be proportional to
R2
R
The north pole of a long horizontal bar magnet is being brought closer to a vertical conducting plane along the perpendicular direction. The direction of the induced current in the conducting plane will be
horizontal
vertical
clockwise
Anticlockwise
An electric current passes through a long straight copper wire. At a distance 5 cm from the straight wire, the magnetic field is B. The magnetic field at 20 cm from the straight wire would be
An electron of mass m and charge q is travelling with a speed v along a circular path of radius r at right angles to a uniform magnetic field B. If speed of the electron is doubled and the magnetic field is halved, then resulting path would have a radius of
2r
4r
A galvanometer acting as a voltmeter should have
low resistance in series with its coil
low resistance in parallel with its coil
high resistance in series with its coil
high resistance in parallel with its coil
A galvanometer can be changed into an ammeter by using
low resistance shunt in series
low resistance shunt in parallel
high resistance shunt in series
high resistance shunt in parallel
A proton moving vertically downward enters a magnetic field pointing towards north. In which direction proton will deflect?
East
West
North
South
A coil of n number of turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current of strength I is passed through the coil, the magnetic field at its centre is
