The document discusses torque and electric motors. Torque is a twisting force that produces rotation. In electric motors, torque is applied to a coil wound into a loop, causing it to turn. As the coil turns, the torque changes based on the angle between the magnetic field lines and the plane of the coil. Measuring devices like galvanometers and ammeters also operate using the principle of torque generated by a current-carrying coil in a magnetic field. Galvanometers can detect small electric currents due to their sensitive design, while ammeters are constructed to measure heavier currents using a spinning coil and pointer system.

1. Torque & Motors

2. Electric Motor

3. Torque is the
tendency of a
force to rotate an
object about an
axis, fulcrum or
pivot. Just as a
force is a push or
a pull, a torque
can be thought of
as a twist.
Torque is a force
that produces
rotation.
Torque has the
symbol, 𝞃, and
units of newton

4. Dc
Motor

5. Dc
Motor

6. Dc
Motor

7. Dc
Motor

9. In electric
motors, it is a
conductor
wound into a
coil or loop
that turns
when torque is
applied.
The force in
the equation
for torque
comes from
the motor

10. As the coil turns
the torque
changes
because the
angle between
the magnetic
field lines and
the plane of the
coil (θ) is also
changing.
The torque is
maximum when
the θ = 0 and
zero when θ =

11. If a radial
magnetic field is
used instead,
the field lines
are curved
between the
north and south
poles of the
magnet.
The angle θ
between the
plane of the coil
and the field
lines is kept

12. Measuring devices

13. Galvanometer
Galvanometer is an electromechanical
instrument which is used for the
detection of electric currents through
electric circuits. Being a sensitive
instrument, Galvanometer can not be
used for the measurement of heavy
currents. However we can measure
very small currents by using
galvanometer but the primary purpose

14. Galvanometer works on the principle of
conversion of electrical energy into mechanical
energy. When a current flows in a magnetic
field it experiences a magnetic torque. If it is
free to rotate under a controlling torque, it
rotates through an angle proportional to the
current flowing through it.
There are five essential parts of a
Galvanometer.
1. A U-shaped permanent magnet with
concave poles.

15. Ammeter

16. Ammeter is constructed with a small
spinning coil of wire in the field of a
permanent magnet. The coil is
attached to a thin pointer that
traverses a calibrated scale. A tiny
torsion spring pulls the coil and
pointer to the zero position.
When a direct current (DC) flows
through the coil, the coil generates a
magnetic field. This field acts against

21. SUMMARY

22. Thank you
for listening
Group 5