electromagnetic induction

Question 1

electromagnetic induction

Answer 1

process through which an induced emf is produced in a conductor due to a changing magnetic field

Question 2

faraday’s law of electromagnetic induction

Answer 2

state that the magnitude of the induced emf in a circuit is directly proportional to the rate of change of magnetic field line in the circuit

Question 3

lenz’s law

Answer 3

states that the direction of the induced emf and hence the induced current in a closed circuit is always such that its magnetic effect opposes the motion or change producing it

Question 4

alternating current generator

Answer 4

transforms mechanical energy into electrical energy

Question 5

how ac generator works

Answer 5

when a force is applied to turn the coil between the magnets, the change in magnetic flux creates an induced emf and hence an induced current in the coil. the slip rings which are always in contact with the carbon brushes as the axle rotates, transfer the induced current in the coil to the external circuit

Question 6

graph

Answer 6

induced emf is max- plane of the coil is parallel to the magnetic field
induced emf is zero- plane of the coil is perpendicular to the magnetic field

Question 7

transformer

Answer 7

device that changes a high alternating voltage to a low alternating voltage or vice versa

Question 8

structure of a transformer

Answer 8

laminated soft iron core consists of thin sheets of soft iron insulated from on another by coats of lacquer to reduce heat loss
soft iron is easily magnetised and demagnetised, ensures better magnetic flux linkage between the two coils

Question 9

how a transformer works

Answer 9

the primary coil is connected to an alternating voltage (the input voltage) which set up a varying magnetic field in the in the laminated soft iron core. an emf is induced on the secondary coil, this voltage is called the output voltage. since the circuit is closed, a current is also induced in the coil.

Question 10

step up transformer

Answer 10

higher output voltage than input voltage

Question 11

step down transformer

Answer 11

lower output voltage than the input voltage

Question 12

solution to reduce power loss

Answer 12

use step up transformers which reduce the current in the cables by increasing the transmission voltage

Question 13

cro

Answer 13

x shift, y shift
y gain is the vertical scale that amplifies the vertical deflection of the input
time base is the horizontal scale that adjusts how quickly the electron beam sweeps horizontally across the screen