CBSE
Multiple Choice QuestionsA wire carrying current I and other carrying 2I in the same direction produce a magnetic field B at the mid-point. What will be the field when 2I wire is switched off?
B/2
2B
B
4B
An electron, moving in a uniform magnetic field of induction of intensity B, has its radius directly proportional to:
its charge
magnetic field
speed
none of these
An electron accelerated through a potential difference enters into a uniform transverse magnetic field and experience a force F. If the accelerating potential is increased to 2V, the electron in the same magnetic field will experience a force :
F
F/2
2F
Which of the following has the minimum resistance?
Voltmeter
Millivoltmeter
Ammeter
Milliameter
A small circular flexible loop of wire of radius 'r' carries a current I. It is placed in a uniform magnetic field B. The tension in the loop will be doubled if :
I is doubled
B is halved
r is doubled
Both B and I are doubled
In a cyclotron, if a deuteron can gain the energy of 40 MeV, then a proton can gain the energy of:
40 MeV
80 MeV
20 MeV
60 MeV
The certain amount of current when flowing in a properly set tangent galvanometer produces a deflection of 45°. The current be reduced by a factor of ✓3, the deflection would :
decrease by 30°
decrease by 15°
increase by 15°
increase by 30°
A galvanometer has a resistance of 400 Ω and deflects full scale for a current of 0.2 mA through it. The shunt resistance required to covert it into 3A ammeter is :
0.027 Ω
0.054 Ω
0.0135 Ω
none of these
A uniform magnetic field is at a right angle to the direction of motion of proton. As a result, the proton describes a circular path of radius 2.5 cm. If the speed of proton is doubled then the radius of the circular path will be :
0.5 cm
2.5 cm
5.0 cm
7.5 cm
Two parallel wires carrying current in the same direction attract each other because of :
the potential difference between them
mutual inductance between them
the electric force between them
the magnetic force between them
