An electron moves on a straight line path XY as shown. The abcd is a coil adjacent in the path of the electron. What will be the direction of the current, if any induced in the coil?
abcd
adcb
the current will reverse its direction as the electron goes past the coil
the current will reverse its direction as the electron goes past the coil
A galvanometer of resistance, G is shunted by a resistance S ohm. To keep the main current in the circuit unchanged,the resistance to be put in series with the galvanometer is
A thermocouple force towards the conductor produces an emf of 40 μ V/oC in the linear range of temperature. A galvanometer of resistance 10 Ω whose sensitivity is 1μA/div, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be.
0.5oC
1oC
0.1oC
0.1oC
Charge q is uniformly spread on a thin ring of radius R. The ring rotates about its axis with a uniform frequency f Hz. The magnitude of magnetic induction at the centre of the ring is
μoqf / 2R
μoq / 2fR
μoq / 2πfR
μoq / 2πfR
A short bar magnet of magnetic moment 0.4 JT-1 is placed in a uniform magnetic field of 0.16T. The magnet is stable equilibrium when the potential energy is
-0.64 J
zero
-0.082 J
-0.082 J
A potentiometer circuit is set up as shown. The potential gradient across the potentiometer wire is k volt /cm and the ammeter, present in the circuit, reads 1.0 A when the two-way key is switched off. The balance points, when the key between the terminals (i) 1 and 2 (ii) 1 and 3, is plugged in, are found to be at lengths l1 and l2 cm respectively. The magnitudes, of the resistor R and X, in ohm, are then, equal respectively, to
k (l2 -l1) and kl2
kl1 and k (l2-l1)
k (l2 - l1) and kl1
k (l2 - l1) and kl1
A galvanometer has a coil of resistance 100 Ω and gives a full-scale deflection for 30 mA current. If it is to work as a voltmeter of 30 V range, the resistance required to be added will be
900 Ω
1800
500 Ω
500 Ω
A square current carrying loop is suspended in a uniform magnetic field acting in the plane of the loop. If the force on one arm of the loop is , the net force on the remaining three arms of the loops is
3
-
A particle having a mass of 10-2 kg carries a charge of 5 x 10-8 C. The particle is given an initial horizontal velocity of 105 ms-1 in the presence of electric field and magnetic field. To keep the particle moving in a horizontal direction. it is necessary that
1) should be perpendicular to the direction of velocity and should be along the direction of velocity
2) Both and should be along the direction of velocity.
3) Both and are mutually perpendicular and perpendicular to the direction of velocity
4) should be along the direction of velocity and should be perpendicular to the direction of velocity.
(1) and (3)
(3) and (4)
(2) and (3)
(2) and (3)
C.
(2) and (3)
Both and should be along the direction of velocity and Both and are mutually perpendicular and perpendicular to the direction of velocity.
A current loop consists of two identical semicircular parts each of radius R, one lying in the x-y plane and the other in x-z plane. if the current in the loop is i. The resultant magnetic field due to the two semicircular parts at their common centre is