For Fleming's left-hand rule, write down the three things that are to each other, and next to each one write down the finger or thumb that represents it.
Important Questions on Electromagnetic Forces
Look back at the diagram of the relay shown in the figure below.
Why is the coil fitted with a soft iron core?
List two ways to increase the force on a current-carrying conductor in a magnetic field.
What is the force on a current-carrying conductor that is parallel to a magnetic field?
Copy and complete the sentence below, choosing the correct words from the list to fill the three gaps.
Electromagnets are used in ____, _____ and _____.
(batteries, electric bells, relays, lamps, motors, resistors)
Copy the sentence below, choosing the correct word from each pair.
When a coil carrying a _____ (current / voltage) is placed in a _____ (magnetic / electric) field, there will be a _____ (lifting / turning) effect on the coil, which makes the coil_____ (rotate / attract).
When a current flows across a magnetic field, a force acts on it. Fleming's left-hand rule shows the relative directions of current, field and force. Write down which of these quantities each finger represents.
a. Thump
b. First Finger
c. Second Finger
The diagram shows the circuit diagram and simple construction of an electric bell.
Put the following sentences in the correct order to explain how the bell operates.
- A current flows through the electromagnet.
- At the same time, the circuit is broken at point A.
- Someone presses the bell push.
- The circuit is completed again at A.
- The electromagnet attracts the iron armature.
- The hammer strikes the gong.
- The springy metal pulls the hammer back.
