8TH GRADE PRACTICE
Physics Problems: Magnetic phenomena, Grade 8
Magnetic fields, electromagnets and motor.
Here the conditions and analysis of the solution can be read without an account. In the simulator, you need to collect the same analyzes yourself: “Given,” formulas, order of steps and answer.
Problem statements
The answer options are there to check against, and the walkthrough opens under each problem.
Problem #61
Magnetic field and electromagnetEvaluate the statement: A form of matter that acts on magnets, moving charges, and current-carrying conductors.
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Magnetic lines outside a permanent magnet are directed from the north pole to the south pole and do not intersect.
Answer
Problem #62
Magnetic field and electromagnetEvaluate the statement: The term “Magnetic field of current” means: A coil carrying current, often equipped with an iron core to enhance the magnetic field.
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In a coil, the fields of individual turns add up, forming a field similar to the field of a strip magnet.
Answer
Problem #63
Magnetic fieldWhat change, while maintaining the size of the coil, usually increases its magnetic effect?
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Answer
Problem #64
Magnetic field action and motorEvaluate the statement: A magnetic field acts as a force on a current-carrying conductor if the current is not directed along the field lines.
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The direction of the force is determined by the left-hand rule, taking into account the direction of the current and magnetic induction.
Answer
Problem #65
Magnetic field action and motorEvaluate the statement: The concept “Electric motor” means: The Earth creates a magnetic field that orients the compass needle approximately along the magnetic meridian.
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Forces on opposite sides of the frame create torque, and switching the direction of the current maintains rotation.
Answer
Problem #66
Electric motorA conductor 0.1 m long is perpendicular to a field of induction 0.2 T. A current of 3 A flows through it. Find the force.
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Answer
The theory behind these problems
Work through the topic if a problem will not give in.
Formulas by topic
Look up symbols and units of measurement in the reference.