Cells, Series and Parallel Circuits Flashcards
Cells are a source of what type of energy?
Electrical energy
What do we call a cell in common everyday language?
A battery
What is an electrolyte?
- Is a solution
- that can conduct
- an electrical current
What does an electrolyte consist of?
- positive (+) and negative (-) particles
- we call these ions
What happens when a circuit is closed?
- a chemical reaction occurs
- the chemical energy is converted into electrical energy
- A current flows
How is current conducted?
- in the electrolyte there are pieces of two different metals eg zinc and copper
- The two metals make the + and - poles of the cell (they are known as electrodes)
- When they are connected to an external circuit, the + ions are attracted to the - pole and the - ions are attracted to the + pole.
- There is potential difference between the poles
- Energy is transferred to charges in an external circuit
- The current flows through the external circuit
Schematic representation
chemical potential energy (ions before they are separated) ——-> Kinetic (movement) energy of charges (electrical energy)
Draw the components of a circuit
-
-
What are the factors that influence resistance?
-Type of conductor
What is a connector?
- substances that conduct an electrical current
- offer little resistance against the flow of charge
- metals like copper, silver and iron
[TRUE or FALSE]
All conductors, even good conductors, heat up if current flows through it
True
What when current flows?
the electrons collide with the particles of the conductor
What is a rheostat?
- It is a variable resistor
- used for example to set a stove plate higher or lower
Resistor?
- has high resistance against the flow of current
- is the component in a circuit that can control the energy transfer in the current and comes into useful forms
- is a weak conductor of electricity
What is the unit of resistance?
ohm (Ω)
What does Potential difference mean?
the difference in potential energy between two points
What is the symbol for potential difference
V (volts)
What is used to measure potential difference
voltmeter
How is a voltmeter connected?
- always connected in parallel
- over a resistor or a cell/battery
Potential difference is measured in
volts (V)
Potential difference is also called?
voltage
What are Conductors?
- metals that are used as connectors in a circuit
- offer resistance against the flow of charge (although very little)
- Little of the energy is lost due to heat(check this one)
What happens when a conductor heats up?
-current is weaker (resistance increases)
What happens when a conductor heats up?
-current is weaker (resistance increases)
What is a light bulb?
A resistor
[FILL IN THE MISSING WORD]
The more light bulbs (resistors) connected in parallel the 1)_________ the resistance
1) less
Does the total current in the circuit increase or decrease with each parallel resistor that is added?
increases
[FILL IN THE MISSING WORD]
The more light bulbs (resistors) connected in parallel the 1)_________ the resistance
1) less
Do all parallel resistors have the same potential difference?
Yes
[Choose the right answer]
Cells produce
A) a constant potential difference
B) a constant current
A) a constant potential difference
[FILL IN THE MISSING WORD]
The current will depend on the resistance. The bigger the resistance the 1)___________ the current
1) smaller
[FILL IN THE MISSING WORD]
The current will depend on the resistance. The bigger the resistance the 1)___________ the current
1) smaller
How are the electrical outlets in our houses connected, in series or in parallel?
parallel
What will happened if one light bulb blows in the house, will the rest of the lights in the house still glow?
Yes the other lights will still glow, as each light bulb is connect in a separate parallel track
[TRUE OR FALSE]
Resistors are manufactured to accurately control the resistance in circuits
True
How many types of variables are there? and name them?
there are 3 types of variables:
- Independent variable - which is changed
- Dependant variable - which is measured
- controlled variable (s) - which remain(s) the same
When light bulbs are connected in parallel, if the circuit branches then the current will?
Divide
When a current flows through a circuit with light bulbs are connected in parallel, does the whole current flow through each light bulb?
- No
- With parallel connections, there is more than one electrical path that can be followed
The more resistors that are connected in parallel, the total resistance in the circuit 1)________? but the total current in the circuit 2) _________ ?
-1) decreases
(note that it is the TOTAL resistance)
-2) increases
What is needed in order for an electrical current to flow?
A source of electrical energy
What is the direction of current?
- from the positive pole (+) of the battery,
- through the circuit
- to the negative pole
What type of current do we call it when the direction of a current is from positive pole, through the circuit, to the negative pole?
Conventional current
What is used to measure current?
Ammeter
How is a ammeter connected?
- The positive terminal is connected so it is closest to the positive terminal of the battery
- it is always connected in series
Does an ammeter have a low or high resistance?
low
What unit is used to measure current?
ampere (A)
What unit is used to measure current?
ampere (A)
The strength of a current in a circuit decreases if the resistance in the circuit 1) _________
increases
What is the unit for resistance?
ohm (Ω)
What is the unit for potential difference?
volts (V)
What is the unit for current strength?
ampere (A)
What is the formula to calculate resistance?
R = V/I
[TRUE OR FALSE]
Current is controlled in the circuit?
True
[FILL IN THE MISSING WORDS]
1) _________ is directly proportional to the 2) ________ __________ (unless the conductor heats up)
1) Current
2) potential difference
Do cells deliver constant current?
- No
- cells produce a constant potential difference, not a current
[FILL IN THE MISSING WORDS]
Regardless of the number of cells/batteries in a circuit the current can still be very 1)_______?
1) small
[FILL IN THE MISSING WORDS]
Current will be 1) __________ with low resistance and 2) _______________ with high resistance
1) bigger
2) smaller
How many paths are there for a current to flow in a series circuit?
Only one path
At all points in a series circuit the strength of the current is ……..?
the same everywhere
In a series circuit the potential difference is ……..?
divided
In a series circuit the potential difference over the resistors is divide in the same ratio as ….?
the resistance of each resistor
There are two types of cells, namely? Give examples
- 1) wet cells (e.g. car battery)
- 2) dry cells (e.g. cells we put in torches, radios, toys etc)
Do wet and dry cells work on the same principle?
Yes
When cells are connected in series, how are they connected?
the positive pole of the one cell is connected to the negative pole of the following cell
What is a battery?
two or more cells that are connected in series
When cells are connected in parallel, how are they connected?
all the negative poles are connected to the one end and all the positive cells at the other end
