Electricity and Magnetism

Question 1

Electric Current

Answer 1

rate of flow of charge, which may be positively or negatively charged.

Question 2

Coulomb

Answer 2

One Coulomb is the quantity of charge that flows through a point when a current of one ampere flows for one second

Question 3

resistance

Answer 3

ratio of the potential difference V applied across a component to the current I passing through it

Question 4

Ohm

Answer 4

A resistor has a resistance of one ohm if a current of one ampere flows through it when the potential difference across it is one volt

Question 5

electromotive force

Answer 5

the energy converted from other forms to electrical energy per unit charge delivered round a complete circuit

Question 6

potential difference

Answer 6

pd across two points of a circuit is the electrical energy converted to other forms of energy per unit charge passing from one point to another

Question 7

electric field

Answer 7

region of space where a force acts on a stationary charge. The direction of the electric field is the direction of the force on a positive charge

Question 8

Coulomb’s Law

Answer 8

the magnitude of electric force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of their separation

Question 9

electric field strength

Answer 9

electric force per unit positive charge placed at that point

Question 10

electric potential

Answer 10

work done per unit positive charge in bringing a small test charge from infinity to the point

Question 11

electronvolt

Answer 11

A unit of energy equal to the energy gained by an electron when it is accelerated through a potential difference of 1V

Question 12

magnetic field

Answer 12

a region of space where a force acts on a magnetic pole, moving charge particle or current-carrying conductor in the field

Question 13

force on conductor, F

Answer 13

the force of conductor of length L carrying a current I placed at an angle of θ to a region of magnetic field B is given by F=BIL sin θ

Question 14

magnetic flux density

Answer 14

defined as the force per unit length per unit current acting on an infinitely long current carrying conductor placed perpendicularly to the magnetic field.

Question 15

Tesla

Answer 15

If a long straight carrying conductor carrying a current of 1 ampere is placed at right angles to a uniform magnetic field of 1 Tesla, then the force per unit length on the conductor is 1 newton per metre

Question 16

magnetic flux

Answer 16

the product of an area and the component of the magnetic flux density perpendicular to that area

Question 17

magnetic flux linkage

Answer 17

product of the magnetic flux passing through the coil and the number of turns on the coil

Question 18

Faraday’s Law of electromagnetic induction

Answer 18

emf induced in a conductor is directly proportional to the rate of change of magnetic flux linkage or the rate of cutting of magnetic flux.

Question 19

Lenz’s Law

Answer 19

direction of the induced emf is such that it may produce magnetic effects to oppose the change causing it

Question 20

root mean square (rms)

Answer 20

The rms value of an alternative current (or voltage) is the value of a steady direct current (or voltage) that would produce the same average power in a given resistor