·
Electromagnet
- Electric current in a conductor produces a magnetic field around it.
- When a wire is wound into a coil, a electromagnet can be constructed. When electric current flows through the wire, the magnet is turned on. When electric current does not flow through the wire, the magnet is turned off.
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/electromagnet_nhbilt.jpg)
Magnetic Field Patterns of Current Through Different Shapes of Wire
- Current through a straight line
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/mmui9rdk1nkrmfrxqcbh.png)
- Current through a flat circular coil
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/dua0egctuj051jxp7dso.png)
- Current through a solenoid
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/nsr9btrdswlmhdpwyrfa.png)
Force on a Current-Carrying Wire in a Magnetic Field
When a current flows through a wire in a magnetic field,
- Magnetic field is produced by the electric current.
- This magnetic field interacts with the already existing magnetic field.
- The current-carrying wire in a magnetic field experiences force acting on it due to the interaction.
The magnitude of the force on the wire can be increased by
- increasing the magnitude of magnetic field
- increasing current flow in the wire
The direction of the force can be determined using Fleming's left hand rule:
When the thumb, index finger and middle finger of your left hand are held so that they are all perpendicular to each other,
- The thumb points in the direction of force.
- The index finger points in the direction of the original magnetic field.
- The middle finger points in the direction of the current.
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/fleming_s_left_hand_rule_kqda50.png)
Example 1
A metal rod XY is placed in a magnetic field. Wires from a cell are connected to the ends of the rod so that the current flows from X to Y. Describe the effect on the rod.
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/252145/ilqs3sbsnwn6kzyahs2u.png)
- The current in the rod will generate magnetic field around the rod.
- As the generated magnetic field interacts with the magnetic field that the rod is placed in, the rod will feel a force acting on it.
- The rod moves in the direction of the force.
- Using Fleming's left hand rule, we can determine that the direction of the force is pointing out of the screen.