Keypoints

Question 1

What is the law of force between charges

Answer 1

The law of force between charges may be stated as follows: like charges repel, unlike charges attract

Question 2

Electric charge is measured in _____

Answer 2

Electric charge is measured in coulombs (C), which is defined in terms of ampere

Question 3

What is the charge conservation law

Answer 3

The charge conservation law may be stated as follows: The total electric charge in an isolated system, that is, the algebraic sum of the positive and negative charge present at any time, does not change

Question 4

What is Coulomb’s Law

Answer 4

Coulomb’s Law states that the electrostatic force between the two spheres is proportional to the product of the charges and is inversely proportional to the square of their distance apart

Question 5

What is the formula for coulomb’s law

Answer 5

The formula for Coulomb’s Law F = k* q1q2/r^2, where F is the electric force between the two charges Q1 Q2, distance r apart, and k = 9 * 10^9

Question 6

What is the principle of superposition

Answer 6

The principle of superposition states that the total force on q1 will be the vector sum of forces on q1 due to q2 and q3 independently

Question 7

What is an electric field

Answer 7

An electric field is a region where an electric charge experiences a force

Question 8

The formula for calculating electric field charge

Answer 8

The formula for calculating electric field charge is E = F/q where f = force and q = unit charge

Question 9

An electric field can be represented by _____

Answer 9

electric field lines or lines of force

Question 10

What is Gauss’s law

Answer 10

Gauss’s law states that the electric flux through the sphere is proportional to the charge and is independent of the radius of the surface.

Question 11

Gauss’s law applies to any hypothetical closed surface (called _____ ) and enclosing a charge distribution

Answer 11

a Gaussian surface

Question 12

What is electric potential

Answer 12

The electric potential at a point in a field can be defined as the work done per unit charge moving from infinity to the point

Question 13

The unit of potential difference is _____

Answer 13

the volt

Question 14

_____is a device which can store electric charge

Answer 14

A capacitor

Question 15

If two capacitors with capacitances C1 and C2 are connected in series, the effective capacitance is____

Answer 15

C = C1 C2 (C1 + C2)

Question 16

One ohm is the resistance of a conductor through which a current of 1A passes when a potential difference of 1 volt is maintained across its ends.

Answer 16

One ohm

Question 17

The algebraic sum of the current toward any branch point in a network is zero. This is _____

Answer 17

the point rule

Question 18

The algebraic sum of the e.m.f.s in a loop equals the algebraic sum of the IR products in the same loop – This is ____

Answer 18

the loop rule

Question 19

_______ moving in a uniform electric field follows a parabolic path because it is subjected to a constant acceleration

Answer 19

A charged particle

Question 20

______ is the mass liberated in electrolysis by 1 coulomb.

Answer 20

The electrochemical equivalent of a substance

Question 21

_______ is proportional to the quantity of electricity passed, i.e. to the product of current and time

Answer 21

The mass of a substance liberated in electrolysis

Question 22

Applications of electrolysis

Answer 22

electroplating, electrotyping and the production of pure metals.

Question 23

The commercial unit of electrical energy is ______ which is the energy expended in an electric circuit at the rate of one kilowatt for one hour

Answer 23

the kilowatt-hour (KWh)

Question 24

Three classification of magnetic materials

Answer 24

Magnetic materials are classified as follows:
Diamagnetic ( μr slightly less than 1),
Paramagnetic (μr slightly greater than 1),
Ferromagnetic (μr much greater than 1 and not constant).

Question 25

_____ is a great magnet

Answer 25

The earth

Question 26

At the magnetic equator,_______ is horizontal and at the magnetic poles, it is vertical.

Answer 26

a dipping compass needle

Question 27

The variation of the compass from a north-south direction is called ______

Answer 27

the declination

Question 28

According to ______, whenever there is a change in the magnetic flux linking a coil or a circuit, and e.m.f (and hence a current ) is induced in the circuit, it lasts only so long as the change is taking place

Answer 28

Faraday’s law of electromagnetic induction

Question 29

The ______ is the steady direct current which converts electrical energy to other forms of energy

Answer 29

effective value of an alternating current (also called the r.m.s value)

Question 30

______ shows the effective or r.m.s value of the current.

Answer 30

An ammeter

Question 31

The frequency of the mains supply in Nigeria is ______

Answer 31

50Hz

Question 32

_____ states that if A, B, C are three different metals, the thermoelectric e.m.f of the couple AC is equal to the sum of the e.m.f of the couple AB and BC over the same temperature range.

Answer 32

The law of intermediate metals

Question 33

______ states that the e.m.f of a thermocouple with junctions at temperature θ1 and θ3, is the sum of the e.m.f’s of two couple of the same metals with junctions at θ1 and θ2, and at θ2 and θ3, respectively.

Answer 33

The law of intermediate temperature

Question 34

________ determines which element the atom is.

Answer 34

The number of protons (the atomic number Z )

Question 35

______ is a collection of such atoms whose nuclei have the property of randomly but spontaneously emitting radiation.

Answer 35

A radioactive source

Question 36

______ is a helium nucleus consisting of 2 protons and 2 neutrons and when an atom decays by alpha emission, its mass number decreases by 4 it's atomic number by 2.

Answer 36

An alpha particle

Question 37

When _____ occurs, a neutron changes into a proton and an electron. The proton remains in the nucleus and the electron is emitted as a beta particle.

Answer 37

beta decay