cells
What is the difference between a cell and a battery?
A cell is a single source of electrical energy
A battery is made up of two or more cells connected together.
what are two advantages of PVC over EMT conduit?
easier to work
cheaper/cost less
The molecular theory of magnetism states that magnetism in materials is mainly due to
Electron spin
What is electrical Power?
Define a Watt?
Electrical power is the rate at which electrical energy is used or converted in a circuit
one watt is equal to one joule of work being done on a object per second.
What is a primary (Dry cell) and secondary cell (wet cell)? and give one example of each
Primary cell are those that cannot be recharged
example
Secondary cell can be recharged
example
name two places a 2 way switch can be used?
long corridors/hall ways
upstairs and downstairs
large rooms
which direction does magnetic field lines go outside a bar magnet?
Go from North to south
what is the metric unit of power?
Watt
The capacity of a battery is measured in
ampere-hours
how many terminals are there on a 2 way switch
Ans;3
l
1
2
Name a material that is strongly attracted to a magnet?
Iron
What is the main formula for calculating POWER?
P = V x I
where P= Power in watts
V= Voltage (volts, V)
I = Current (amperes, I)
Name 4 methods of battery charging
1.Initial charging
2.normal charge
3.Equalizing charge
4.floating charge
5.fast charge
what are travelers in a 2 way switch?
they are wires used to connect the 2 way switches
The corkscrew (right hand screw rule) gives the direction of........................
magnetic field around a conductor
state the other power formulas
P= Isq x R
P=vsq /R
What is the instrument used to measure a battery specific gravity?
A Hydrometer
Name the 4 test that must be carried out on a wiring installation before it can be used?
verification of polarity
Continuity test
Effectiveness of earthing
Insulation resistance test
Using the right-hand grip rule if the thumb points in the direction of the current the curled fingers point....
magetic field
A DC motor is connected to a 12v battery and draws 4A. What is the power drawn?
P= V x I
12 x 4 = 48 watts