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medium importancemedium difficulty5 min

Fleming's right hand rule

Fleming's right hand rule helps find the direction of induced current when a conductor moves in a magnetic field.

In one line: Right hand gives induced current.

Practice This Concept

Understand it

Stretch the thumb, forefinger, and middle finger of the right hand mutually perpendicular to each other. The forefinger points in the direction of magnetic field, the thumb points in the direction of motion of the conductor, and the middle finger shows the direction of induced current. This rule is especially useful in generators and induction-based questions.

Example

If a conductor moves upward in a magnetic field from north to south, the right hand rule gives the direction of the induced current in the conductor.

Formula and rule

Forefinger = magnetic field, thumb = motion of conductor, middle finger = induced current, all at right angles.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

  1. 1A wire moving to the right in a magnetic field may produce current upward, depending on field direction.
  2. 2The right hand rule helps determine that current direction quickly in exam problems.

Method you can reuse

  1. 1Use the right hand.
  2. 2Stretch thumb, forefinger, and middle finger at right angles.
  3. 3Point forefinger along magnetic field.
  4. 4Point thumb along motion.
  5. 5Middle finger gives induced current direction.

Sketch it in your answer

Draw a right hand with three perpendicular fingers labelled field, motion, and induced current.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

In Fleming's right hand rule, what does the middle finger show?

Think first, then show answer
The middle finger shows the direction of induced current in the conductor when it moves in a magnetic field.

Common wrong answer

A common wrong answer is to use the left hand, which belongs to force on current, not induced current.

Don't mix this up

Students often use the left hand here or mix the directions of motion and current.

Exam tip

Right hand is for induced current; left hand is for force in motor questions.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

State the rule, determine induced current direction, or connect the rule to a generator.
  1. 1

    Enough for 1 mark

    Fleming's right hand rule helps find the direction of induced current when a conductor moves in a magnetic field.

  2. 2

    Add for 2 marks

    Stretch the thumb, forefinger, and middle finger of the right hand mutually perpendicular to each other.

  3. 3

    Add for 3 marks

    A wire moving to the right in a magnetic field may produce current upward, depending on field direction.

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