Science Cycle Test 12 October Flashcards
Ammeters are connected in …
Series
Voltmeters are connected in …
Parallel
Function of the cell
Supply energy to the charges which move through the conductors and cause an electric current
The chemical energy in a cell in converted into
Electrical energy
Potential difference(V)=
Energy transferred (W in joules)
———————————————
Charge (Q in coulombs)
Conventional current
conventional current is from positive terminal to the negative terminal. The behaviour is like positive charge carriers will cause the current to flow.
Resistance
A materials opposition to the flow of electric current
What is resistance measured with
Multimeter
What do multimeters measure
Direct current, alternating current, potential difference, and resistance
Resistance is measured with which unit
Ohm
What are alloys
Mixtures if metals and have a Hugh resistance
What is nichrome
Mixture of nickel and chrome , is an alloy which is generally used as a resistor
Ohms law
The current through a conductor is directly proportional to the potential difference across a conductor at a constant temperature
Resistance formula
Resistance (R ohms)=potential difference (V)/current (I unit A)
What is a short circuit
Extra path for the charges between two points in a circuit occurs
If a copper wire is connected across a lightbulb the electric current will flow through …
The copper wire not the light bulb because the copper wire offers a lower resistance
Charges will take the path of ..
Least resistance
What is used to trip the the power if a short circuit occurs
Contact-breaker
Factors which influence resistance
-type of conductor (compare copper and nichrome)
-thickness of conductor
-length of conductor
-temperature of conductor
Cells in series cause what do happen to potential difference and current strength
Cause a greater potential difference and the current strength increases proportionally
A higher resistance leads to a …
Weaker current strength
Deductions we can make about resistors in series
-the current strength in a series circuit is the same throughout the circuit
-the potential different is divided between the resistors :V total=V1+V2+V3
-the total resistance is the sum of the separate resistors :R total =R1+R2+R3
What happens to the resistance if more resistors are in parallel
They do not increase the resistance if tepee circuit (two lanes on the highway help the traffic flow)the energy transferred to each of the light bulbs is the same as the energy transferred to one lightbulb
What are deductions we can make on lightbulbs(resistors in parallel)
-the potential difference Ina parallel circuit remains constant
-the current strength is divided between the resistors : Current total =I1+I2+I3
-resistors in parallel have a lower resistance that resistors in series
How to calculate effective resistance of resistors in parallel
- 1
— =— +— +—
Re. R1. R2. R3
- 1
Alkali metals react with water to produce …
Alkaline solutions and hydrogen and the speed of the reaction increases down the group
General chemical reactions for metals and non-metals (3)
- Metal + oxygen ~> metal oxide
2.non metal + oxygen~> non-metal oxide
3.metal + water ~> metal hydroxide + hydrogen
Test for hydrogen
Hydrogen makes a squeaky pop with a lighted splint
Test for carbon dioxide
Carbon dioxide gas
Lime water (clear colourless)
Turns into lime water (cloudy milky )
Test for oxygen
Oxygen relights a glowing splint
Halogens react with water to produce …
Acidic solutions
Where are alkali metals stored
In oil
Relative hardness of potassium and sodium
Potassium and sodium an doesn’t and can be cut with a knife
Potassium and sodium reaction with water
-Sodium catches alight immediately with contact with H2O
-potassium has a purple flame
-both spin around on the surface of the H2O and explode loudly after some time
Lustre of sodium and potassium
shiny metallic when cut open
The Softness and reactivity increases when…
Going down the groups in the periodic table
The physical state of Chlorine
Gas
The physical state of bromine
Liquid
The physical state iodine
Solid
What happens to densities going down the groups
Densities increase
Melting and boiling points increase when…
Going down the groups
Metal + oxygen ~>
Metal oxide
Are metal oxides acidic or basic
Basic .Red litmus turns to blue
Non-metal +oxygen~>
non-metal oxide
Are non-metal oxides acidic or basic
Acidic .Blue litmus turns red
Metal+water ~>
metal hydroxide + hydrogen
Are metal hydroxides acidic or basic
Basic .Red litmus turns blue
How to test for hydrogen
Hydrogen makes a squeaky pop with a lighted splint
Test for carbon dioxide
Extinguishes a flame turns lime water (cloudy /milking )
Test for oxygen
Oxygens relights a growing splint
Text for chlorine
Has a very distinct smell, chlorine bleaches litmus paper
What increases going down the groups in the periodic table
Densities
Softness and reactivity
Melting and boiling points
