CBSE
Multiple Choice QuestionsA cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively with and without being short-circuited through a resistance of 10 Ω. Its internal resistance is
1.0 Ω
0.5 Ω
2.0 Ω
2.0 Ω
A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction in
such a way that its axis makes an angle of 60o with.
The magnetic flux linked with the disc is
0.02 Wb
0.06 Wb
0.05 Wb
0.05 Wb
What is the value of inductance L for which the current is a maximum in a series LCR circuit with C =10μ F and ω = 1000 s-1
100 mH
1 mH
cannot bec calculated unless R is known
cannot bec calculated unless R is known
Under the influence of a uniform magnetic field. a charged particle is moving in a circle of radius R with constant speed v. The time period of the motion.
depends on v and not on R
depends on both R and v
is independent of both R and v
is independent of both R and v
A transforner is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately:
30%
50 %
90 %
90 %
When a charged particle moving with velocity 
is subjected to a magnetic field of induction 
, the force on it is non-zero. This implies that
angle between 
is necessarily 
angle between 
can have any value other than 
angle between 
can have any value othe than zero and 
angle between can have any value othe than zero and
Two coils of self-inductances 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is
10 mH
6 mH
4 mH
4 mH
The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance
0.138 H
138.88 H
13.89
1.389 H
If the flux associated with a coil varies at the rate of 1wb/min the induced emf is
zero
6oV
1V
A circular coil of mean radius of 7 cm and having 4000 turns is rotated at the rate of 1800 revolutions per minute in the earth's magnetic field (B=0.5 gauss), the emf induced in coil will be
1.158 V
0.58 V
0.29 V
5.8 V
