An electron moving with kinetic energy 6.6 * 10-14J enters a magnetic field 4 * 10-3T at right angle to it.The radius of its circular path will be nearest to
A closely wound flat circular coil of 25 turns of wire has diameter of 10 cm which carries current of 4 A, the flux density at the centre of a coil will be
Flux density = 2 * π * N * i/10r
or, = 12.56G or 1.25 * 10-3T
A cyclotron is operating at a frequency of 12 * 106 Hz. Mass of deuteron is 3.3 * 10-27 kg and charge on deuteron is 1.6 * 10-19 induction of the neccessary magnetic field is
The strength of the transverse magnetic field required to bend photoelectrons of maximum kinetic energy with in a circle of radius 50 cm when light of wavelength 4000Å is incident on barium emitter is (work function of barium is 2.5 eV)
key idea: Body performing circular motion is always acted upon by a centripetal force provided by magnetic field. If the kinetic energy of photoelectrons emitted from the metal surface is E1 and W the work function them from Einstein's photoelectric equation, we have Eh = hv -W where v is frequency and h the Planck's constant
Putting the numercial values from the question, we have
A body performing circular motion is acted upon by a force directed towards its centre Also the magnetic force On equating.
At a certain place, the horizontal component of earth’s magnetic field is times of its vertical component. the angle of dip at that place is
A magnet makes 30 oscillations per minute in the earth’s magnetic field. If the magnetic field is doubled. The period of oscillation of magnet is
n1 = 30 oscillation/min
n1 = 1/2 oscillation/s
T1 = 2s
In the circuit shown in the figure, what is the value of just after pressing the key K?
A long solenoid has 100 turns/meter and a current of 3.5 A is flowing through it. If it is filled with material of relative permeability (μr = 20) then magnetic field within the solenoid will be xπ × 10–4, find x?
B = µ0µRni
A bar magnet is freely suspended in such a way that, when it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place, where dip angle is 30° and 15 oscillations per minute at a place, where dip angle is 60°. Ratio of total earth's magnetic field at these two places is x : 9√3, find x :-
A square loop ABCD carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current i, the net force on the loop will be Find the value of k.
A square metal wire loop of side 10 cm and resistance 1Ω moved with a constant velocity v in a uniform magnetic field B = 2T as shown in figure. The magnetic field is perpendicular to the plane of the loop and directed into the paper. The loop is connected to a network of resistors, each equal to 3Ω. What should be the speed of the loop in m/s so as to have a steady current of 1mA in the loop?
The given network PQRS is balanced Wheatstone's bridge. Hence the resistance connected in the diagonal arm PR becomes ineffective. The net effective resistance of the network is
The total resistance of the loop + network is
R = 1 + 3 = 4Ω
Induced current in the network,
v = 2 × 10–2 m/s = 2 cm/s
An AC source of angular frequency ω is fed across a resistor R and a capacitor C in series. The current registered is I. If now the frequency of source is changed to ω/3 (but maintaining the same voltage), the current in the circuit is found to be halved. The ratio of reactance to resistance at the original frequency ω is then find the value of x.
At angular frequency ω, the current in RC circuit is given by