Electricity and Magnetism Answers

One end of a simple rectangular wire-loop current balance is inserted into a solenoid. A force of
3.0×10−3N
is found to act on this end when a current of 2.0A is flowing in it. If the length of the conductor forming the end of the the wire-loop is 0.10m. What is the magnetic flux density in the solenoid?
0.043T
0.26T
0.43T
0.015T

A rectangular coil of dimensions 20cm by 15cm lies with its plane parallel to a magnetic field of
0.5W/m2
. The coil, carrying a current of 10A experiences a torque of 4.5Nm in the field. How many loops has the coil?
100
60
30
20

4 A small object has charge Q. Charge q is removed from it and placed on a second small object. The two objects are placed 1 m apart. For the force that each object exerts on the other to be a maximum, q should be:
2Q
Q
Q/2
Q/4

2 A uniform electric field of 200 N/C is in the x-direction. A point charge of
3μC
is released from rest at the origin. What is the kinetic energy of the charge when it is at x = 4 m?

2.4×10−2J

1.6×10−2J

3.6×10−2J

4.8×10−2J

1 The electron beam in a television tube consists of electrons accelerated from rest through a potential difference of about 20 000V. What is the speed of the electrons? (Ignore relativistic effects). Electron rest mass is
9.11×10−31
kg and electronic charge is
1.6×10−19 C.

8.4×107
m/s

3.8×106
m/s

6×106
m/s

4.7×107
m/s

Two dipoles each of dipole moment p are placed 2r distance apart. What is the electric field intensity at the midpoint of line joining the dipoles? please derive.

Two long parallel wires carry currents of 1.13 A and 4.59 A. The magnitude of the force per unit length acting on each wire is 7.59 × 10-5 N/m. Find the separation distance of the wires expressed in millimeters.

Two large horizontal metal plates are separated by 4mm.
The lower plate is at a potential of (-)6v.What potential
should be applied to the upper plate to create field strength
of 4000v/m upwards in the space between the plates?
+22v
+10v
-10v
-22v

Which of the following is not correct?
A changing electric field can produce a changing magnetic field
A steady magnetic field produces a steady current
A changing magnetic field can produce a changing current
A changing magnetic field can produce a steady electric field

A circuit flows in a wire of cross section with the free electron traveling with a mean drift velocity v. If an equal current flows in a wire of the same material of twice the radius, what is the mean drift velocity?
V/4
V/2
2v
4v