CBSE
Multiple Choice QuestionsA coil of self -inductance L is connected in series with a bulb b and an AC source. Brightness of the bulb decreases when
frequency of the AC source is decreases
number of turns in the coil is reduced
a capacitance of reactance Xc=XL is included in the same circuit
a capacitance of reactance Xc=XL is included in the same circuit
A conducting square frame of side 'a' and a long straight wire carrying current I are located in the same plane as shown n the figure. The frame moves to the right with constant velocity 'v'. The emf induced in the frame will be proportional to
The current (I) in the inductance is varying with time according to the plot shown in a figure.
A current loop in a magnetic field
experiences a torque whether the field is uniform or non-uniform in all orientations
can be in equilibrium in one orientations
can be an equilibrium in two orientations, both the equilibrium states are unstable
can be an equilibrium in two orientations, both the equilibrium states are unstable
The current i in a coil varies with time as shown in the figure. The variation of induced emf with time would be
An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude.
zero
A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is
zero
is at higher potential
and R is at higher potential
and R is at higher potential
A long solenoid has 1000 turns. when a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4x10-3 Wb. The self inductance of the solenoid is,
3H
2H
1H
1H
The rate of increase of thermo - emf with temperature at the neutral temperature of a thermocouple
is zero
depends upon the choice of the two materials of the thermocouple
is negtive
is negtive
A coil of resistance 400 is placed in magnetic field. If the magnetic flux Φ (Wb) linked with the coil varies with time t (sec) as Φ = 50t2 +4.
The current in the coil at t= 2 s is
0.5 A
0.1 A
2 A
2 A
