Unit III: Magnetism and magnetic effects of electric current - Online Test
Q1. The magnetic field at the
center O of the following current loop is
Answer : Option A
Explaination / Solution:
Q2. An electron moves straight
inside a charged parallel plate capacitor of uniform charge density σ. The time
taken by the electron to cross the parallel plate capacitor when the plates of
the capacitor are kept under constant magnetic field of induction 
is
is
Answer : Option D
Explaination / Solution:
Q3. The force experienced by a
particle having mass m and charge q accelerated through a potential difference
V when it is kept under perpendicular magnetic field is
is
Answer : Option C
Explaination / Solution:
Q4. A circular coil of radius 5
cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of
the coil is
Answer : Option B
Explaination / Solution:
Q5. A thin insulated wire forms
a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli
ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm
respectively. The magnetic induction at the center of the spiral is
Answer : Option B
Explaination / Solution:
Q6. Three wires of equal lengths are bent in the form of loops. One of the loops is circle, another is a semi-circle and the third one is a square. They are placed in a uniform magnetic field and same electric current is passed through them. Which of the following loop configuration will experience greater torque ?
Answer : Option A
Explaination / Solution:
Q7. Two identical coils, each
with N turns and radius R are placed coaxially at a distance R as shown in the
figure. If I is the current passing through the loops in the same direction,
then the magnetic field at a point P which is at exactly at R/2 distance
between two coils is
Answer : Option B
Explaination / Solution:
Q8.
A wire of length l carries a current I along the Y
direction and magnetic field is given by
The magnitude of Lorentz force acting on the
wire is
Answer : Option A
Explaination / Solution:
Q9. A bar magnet of length l
and magnetic moment M is bent in the form of an arc as shown in figure. The new
magnetic dipole moment will be
Answer : Option B
Explaination / Solution:
Q10. A non-conducting charged
ring of charge q, mass m and radius r is rotated with constant angular
speed ω. Find the ratio of its magnetic moment with angular momentum is
Answer : Option C
Explaination / Solution:
