Electro-magnetic Induction

Question 1

what do motors do in terms of energy

Answer 1

convert electrical –> kinetic

Question 2

what do generators do in terms of energy while using electromagnetic induction

Answer 2

convert kinetic –> electrical

Question 3

how does a generator work

Answer 3

• current induced in a wire
• wire cuts through magnetic field lines
• use method of induction to generate electrical energy from chemical energy

Question 4

how can a generator use electromagnetic induction to induce a larger current

Answer 4

• more powerful/stronger magnet with more magnetic fields
• use a coil around the magnet / a wire with lots of turns/ or many thin wires
• use more kinetic energy at the start to cut through the magnetic field lines to have the output of more KE

Question 5

what is another way of current being produced instead of passing the wire by a magnet

Answer 5

if there is a changing magnetic field from the wire current can be induced – this is done by an alternating current (transformers use this method)

Question 6

what is the equation to represent the relationship between number of turns in the coil to voltage

Answer 6

N1/N2 = V1/V2

Question 7

what is the purpose of a step-up transformer

Answer 7

so that voltage is increased

Question 8

what is the purpose of raising the voltage of the national grid to around 400kV

Answer 8

to decrease the current while transporting in the national grid so not much heat is lost through the wires resistance

Question 9

what does a step up transformer look like

Answer 9

when there are less turns in the coil on the first half of the magnet than there are on the second

Question 10

what is the equation that assumes a transformer is 100% efficient

Answer 10

power input = power output
OR
I1V1 = I2V2

Question 11

EXPLAIN HOW A STEP UP TRANSFORMEER WORKS

Answer 11

using the key terms: primary, coil, secondary, flux, a.c., input, output, varying, core

Question 12

what is the benefit of the transformer’s core being made up of soft iron

Answer 12

so the magnetism of the metal can be switched on and off i.e. it is an electromagnet –> easily magnetised and demagnetised

Question 13

what is the benefit of the transformer’s core being laminated

Answer 13

reduces eddy current so this reduces heat loss therefore more efficient

Question 14

what is the equation that links the primary voltage, secondary voltage, primary coil turns and secondary coil turns

Answer 14

V1N1 = V2N2

Question 15

standard magnetic field

Answer 15

goes from the north into the south

Question 16

what is the dynamo effect

Answer 16

using electromagnetic induction to transform kinetic energy into electrical energy

Question 17

two way you can get EM induction

Answer 17

1) an electrical conductor (coil of wire) moving through a magnetic field
2) the magnetic field through an electrical conductor changes (bigger, smaller, reverses)

Question 18

how to test the dynamo effect

Answer 18

connect an ammeter to a conductor and move the conductor through a magnetic field or vice versa and the ammeter will show the magnitude and direction of the induced current