Electromagnets - P3.3

1. 1A magnetic field lines the line along which a plotting compass points

   1. AVerdadero
   2. BFalso
2. 2An electromagnet consists of a [blank_start]coil[blank_end] of insulated wire wrapped around an [blank_start]iron[blank_end] core

   1. Acoil
   2. Biron
3. 3When a current flows through the wire of [blank_start]an electromagnet[blank_end], the [blank_start]iron[blank_end] core becomes strongly [blank_start]magnetised[blank_end]. When the current is switched off, the iron loses its [blank_start]magnetism[blank_end]. Due to this, electromagnets are used in devices such as scrapyard cranes, circuit breakers, electric bells and relays.

   1. Aan electromagnet
   2. Ba circuit
   3. Ciron
   4. Dnickel
   5. Ecobalt
   6. Fmagnetised
   7. Gironised
   8. Hionised
   9. Imagnetism
   10. Jcharge
4. 4When a current is passed along a wire in a magnetic field, and the wire is not parallel to the lines of the magnetic field, a force is exerted on the wire. What is the name of this effect?

   1. AMotor Effect
   2. BWire Effect
   3. CMagnetic field Effect
5. 5In the motor effect, the force:

   1. Ais increased if the current, or strength of the magnetic field, is increased
   2. Bis parallel to the magnetic field
   3. Cat right angles to both the direction of the magnetic field and to the wire
   4. Dis reversed if the direction of either the current or the magnetic field is reversed
6. 6Label this diagram using Fleming's left hand rule.

   

   1. AFirst finger - field
   2. BSecond finger - Current
   3. CThumb - movement (direction of force)
7. 7In a simple electric motor:

   1. Athe speed of the motor is increased by increasing the size of the current
   2. Bthe speed of the motor is decreased by increasing the size of the current
   3. Cthe direction of the motor can be reversed by reversing the direction of the current
8. 8When a current passes through the coil, in an electric motor, the coil spins because:

   1. Aa force acts on each side of the coil due to the motor effect
   2. Ba a resultant force acts on one side of the coil due to the motor effect
   3. Cthe force on one side of the coil is in the opposite direction to the force on the other side
9. 9The 'split-ring' commutator reverses the direction of the current around the coil every half turn. Because the sides swap over each half turn, the coil is always pushed in the same direction.

   1. AVerdadero
   2. BFalso
10. 10Electromagnetic induction is the process of creating a potential difference using a magnetic field.

    1. AVerdadero
    2. BFalso

11. 11Electromagnetic [blank_start]induction[blank_end]: If the direction of movement of the wire/coil is reversed, or the polarity of the magnet is [blank_start]reversed[blank_end], the direction of the induced pd is also reversed. A pd is only induced while there is [blank_start]movement[blank_end].

    1. Ainduction
    2. Breversed
    3. Cmovement
12. 12If an electrical conductor 'cuts' through magnetic field lines, a potential difference is induced across the ends of the conductor.

    1. AVerdadero
    2. BFalso
13. 13The size of the induced potential difference is increased by:

    1. Adecreasing the speed of movement
    2. Bincreasing the speed of movement
    3. Cdecreasing the strength of the magnetic field
    4. Dincreasing the strength of the magnetic field
    5. Edecreasing the number of turns on the coil
    6. Fincreasing the number of turns on the coil

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Test sobre Electromagnets - P3.3 , creado por Elliemd el 07/05/2016.

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